Uplink transmission parameter selection during random access message transmission and retransmission

ABSTRACT

Methods, systems, and devices for wireless communication are described for selecting different uplink transmission parameters for transmission or retransmission of a random access message. A user equipment (UE) may transmit or retransmit a random access message such as a layer 2 or layer 3 (L2/L3) message to a base station during a random access procedure. The UE may select a transmission beam, uplink resource or transmission power for the transmission of the L2/L3 message that differ from those used for transmission of a previous random access message. The selection may be based on path loss associated with synchronization signals or previous transmissions. The selection may also be based on a maximum number of retransmissions.

CROSS REFERENCES

The present application for patent is a Continuation of U.S. patentapplication Ser. No. 15/838,145 by Islam, et al., entitled “UplinkTransmission Parameter Selection during Random Access messageTransmission and Retransmission” filed Dec. 11, 2017, which claimspriority to U.S. Provisional Patent Application No. 62/436,250 by Islam,et al., entitled “Uplink Transmission Parameter Selection During RandomAccess Message Transmission and Retransmission” filed Dec. 19, 2016, andto U.S. Provisional Patent Application No. 62/476,660 by Islam, et al.entitled, “Uplink Transmission parameter Selection During Random AccessMessage Transmission and Retransmission” filed Mar. 24, 2017, andassigned to the assignee hereof.

BACKGROUND

The following relates generally to wireless communication, and morespecifically to uplink transmission parameter selection during randomaccess message transmission and retransmission.

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, and orthogonal frequencydivision multiple access (OFDMA) systems, (e.g., a Long Term Evolution(LTE) system, or a New Radio (NR) system). A wireless multiple-accesscommunications system may include a number of base stations or accessnetwork nodes, each simultaneously supporting communication for multiplecommunication devices, which may be otherwise known as user equipment(UE).

In some wireless systems, a UE may utilize a directional transmission togain access to a medium. For example, a UE may transmit an initialdirectional transmission in order to gain access to a medium. Followingreceipt of a response to the initial directional transmission, the UEmay then transmit a second directional transmission based on thereceived response. However, in some instances, transmission conditionsmay change or transmission directions may be refined, for example, andusing the same direction or the same resources for transmission of thesecond directional transmission as those used for transmission of theinitial directional transmission may not be desirable or the mosteffective.

SUMMARY

In a wireless communications system, such as a millimeter wave (mmW) ora New Radio (NR) system, a base station and a user equipment (UE) mayutilize directional transmissions during a random access channel (RACH)procedure. In some cases, after transmitting a directional initial RACHmessage (e.g., a random access preamble), the UE may receive a randomaccess response from a base station. Prior to transmitting a second RACHmessage (e.g., an L2/L3 message, a Msg3 transmission, a Radio ResourceControl (RRC) connection request message), communication conditions maychange and the parameters used for transmitting the initial RACH messagemay not be appropriate for communication of the second RACH message. TheUE may decide to change one or more uplink transmission parameters(e.g., transmission power, transmission beam, RACH resource, etc.) in anattempt to increase the probability of successful reception of thesecond RACH message at the base station.

In some cases, the UE may not receive confirmation that the base stationreceived the second RACH message. For instance, after a predeterminedtime, the UE may determine that the second RACH message was notsuccessfully received by the base station and the UE may retransmit thesecond RACH message. During retransmission, the UE may again selectdifferent parameters (e.g., transmission power, RACH resource, beam)than those used in the initial RACH message transmission or in previoustransmissions of the second RACH message (e.g., if the UE isretransmitting multiple times). In some cases, the UE may have maximumnumbers of retransmissions associated with a RACH resource, a beam, atransmission power, or a combination thereof.

The described techniques relate to improved methods, systems, devices,or apparatuses that support uplink transmission parameter selectionduring random access message transmission and retransmission.

A method of wireless communication is described. The method may includeidentifying a first uplink transmission beam for a random accessprocedure, transmitting, at a first uplink transmission power, a randomaccess preamble based at least in part on the first uplink transmissionbeam, receiving a random access response message transmitted from a basestation in response to the random access preamble, identifying a seconduplink transmission beam, selecting a second uplink transmission powerbased at least in part on a path loss associated with the random accessprocedure and the identified second uplink transmission beam, andtransmitting, to the base station, a connection request based at leastin part on the second uplink transmission power and the second uplinktransmission beam.

An apparatus for wireless communication is described. The apparatus mayinclude means for identifying a first uplink transmission beam for arandom access procedure, means for transmitting, at a first uplinktransmission power, a random access preamble based at least in part onthe first uplink transmission beam, means for receiving a random accessresponse message transmitted from a base station in response to therandom access preamble, means for identifying a second uplinktransmission beam, means for selecting a second uplink transmissionpower based at least in part on a path loss associated with the randomaccess procedure and the identified second uplink transmission beam, andmeans for transmitting, to the base station, a connection request basedat least in part on the second uplink transmission power and the seconduplink transmission beam.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to identify a first uplinktransmission beam for a random access procedure, transmit, at a firstuplink transmission power, a random access preamble based at least inpart on the first uplink transmission beam, receive a random accessresponse message transmitted from a base station in response to therandom access preamble, identify a second uplink transmission beam,select a second uplink transmission power based at least in part on apath loss associated with the random access procedure and the identifiedsecond uplink transmission beam, and transmit, to the base station, aconnection request based at least in part on the second uplinktransmission power and the second uplink transmission beam.

A non-transitory computer-readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to identify a first uplinktransmission beam for a random access procedure, transmit, at a firstuplink transmission power, a random access preamble based at least inpart on the first uplink transmission beam, receive a random accessresponse message transmitted from a base station in response to therandom access preamble, identify a second uplink transmission beam,select a second uplink transmission power based at least in part on apath loss associated with the random access procedure and the identifiedsecond uplink transmission beam, and transmit, to the base station, aconnection request based at least in part on the second uplinktransmission power and the second uplink transmission beam.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for participating in a beam refinementprocess during reception of the random access response message, whereinthe path loss associated with the random access procedure may bedetermined based at least in part on the beam refinement process.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving, from the base station,multiple synchronization signals, wherein the path loss associated withthe random access procedure may be determined based at least in part onat least one of the multiple synchronization signals.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting the connection requestmay be based at least in part on the second uplink transmission beamdifferent from the first uplink transmission beam.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for selecting the second uplinktransmission power may be based at least in part on a uplinktransmission power command conveyed in the random access responsemessage.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for selecting the second uplinktransmission power comprises adjusting the transmission power conveyedin the random access response message based at least in part on the pathloss.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for selecting the second uplinktransmission power may be further based at least in part on aretransmission number of the connection request.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for selecting the second uplinktransmission power may be further based at least in part on a differencebetween a path loss associated with the random access response messageand a path loss associated with transmission of the random accesspreamble.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for identifying a first uplinktransmission resource for transmission of the random access preamble.Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for selecting, based at least in parton the random access response message, a second uplink transmissionresource different from the first uplink transmission resource. Someexamples of the method, apparatus, and non-transitory computer-readablemedium described above may further include processes, features, means,or instructions for transmitting the connection request using the seconduplink transmission resource.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving, from the base station,multiple synchronization signals, wherein identifying the second uplinktransmission beam for the connection request may be based at least inpart on reception of one or more of the multiple synchronizationsignals.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for selecting a third uplinktransmission beam different than the second uplink transmission beam.Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for retransmitting the connectionrequest based at least in part on the third uplink transmission beam.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving, from the base station, amaximum retransmission number. Some examples of the method, apparatus,and non-transitory computer-readable medium described above may furtherinclude processes, features, means, or instructions for retransmittingthe connection request based at least in part on the maximumretransmission number.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the maximum retransmissionnumber may be associated with at least one of a total number ofretransmission attempts of the connection request or a maximum number ofretransmission attempts of the connection request for each of aplurality of uplink transmission powers.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving, from the base station,an indication of one or more uplink transmit parameters forretransmitting the random access preamble or the connection request,wherein the one or more uplink transmit parameters comprise an uplinktransmit power, an uplink transmission resource, or a combination.

A method of wireless communication is described. The method may includetransmitting a random access preamble as part of a random accessprocedure, receiving a random access response message transmitted from abase station in response to the random access preamble, identifying afirst uplink transmission beam and a first uplink transmission power,transmitting, to the base station, a connection request based at leastin part on the random access response message, the connection requestbeing transmitted using the first uplink transmission beam and at thefirst uplink transmission power, identifying a second uplinktransmission beam different from the first uplink transmission beam,selecting a second uplink transmission power based at least in part on apath loss associated with the random access procedure and the identifiedsecond uplink transmission beam, and retransmitting the connectionrequest based at least in part on the second uplink transmission powerand the second uplink transmission beam.

An apparatus for wireless communication is described. The apparatus mayinclude means for transmitting a random access preamble as part of arandom access procedure, means for receiving a random access responsemessage transmitted from a base station in response to the random accesspreamble, means for identifying a first uplink transmission beam and afirst uplink transmission power, means for transmitting, to the basestation, a connection request based at least in part on the randomaccess response message, the connection request being transmitted usingthe first uplink transmission beam and at the first uplink transmissionpower, means for identifying a second uplink transmission beam differentfrom the first uplink transmission beam, means for selecting a seconduplink transmission power based at least in part on a path lossassociated with the random access procedure and the identified seconduplink transmission beam, and means for retransmitting the connectionrequest based at least in part on the second uplink transmission powerand the second uplink transmission beam.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to transmit a random access preambleas part of a random access procedure, receive a random access responsemessage transmitted from a base station in response to the random accesspreamble, identify a first uplink transmission beam and a first uplinktransmission power, transmit, to the base station, a connection requestbased at least in part on the random access response message, theconnection request being transmitted using the first uplink transmissionbeam and at the first uplink transmission power, identify a seconduplink transmission beam different from the first uplink transmissionbeam, select a second uplink transmission power based at least in parton a path loss associated with the random access procedure and theidentified second uplink transmission beam, and retransmit theconnection request based at least in part on the second uplinktransmission power and the second uplink transmission beam.

A non-transitory computer-readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to transmit a random accesspreamble as part of a random access procedure, receive a random accessresponse message transmitted from a base station in response to therandom access preamble, identify a first uplink transmission beam and afirst uplink transmission power, transmit, to the base station, aconnection request based at least in part on the random access responsemessage, the connection request being transmitted using the first uplinktransmission beam and at the first uplink transmission power, identify asecond uplink transmission beam different from the first uplinktransmission beam, select a second uplink transmission power based atleast in part on a path loss associated with the random access procedureand the identified second uplink transmission beam, and retransmit theconnection request based at least in part on the second uplinktransmission power and the second uplink transmission beam.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the connection request may beretransmitted based at least in part on an absence of a contentionresolution message.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the connection request may beretransmitted based at least in part on receiving a retransmission grantfrom the base station.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving, from the base station, amaximum retransmission number associated with the connection request.Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for retransmitting the connectionrequest based at least in part on the maximum retransmission number.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the maximum retransmissionnumber may be associated with at least one of a total number ofretransmission attempts of the connection request or a maximum number ofretransmission attempts of the connection request for each of aplurality of uplink transmission powers.

A method of wireless communication is described. The method may includereceiving, at a first uplink transmission power and over a first randomaccess resource, a random access preamble transmitted from a UE over afirst uplink transmission beam, transmitting a random access responsemessage in response to the random access preamble, receiving aconnection request based at least in part on the random access responsemessage, transmitting, to the UE, a signal indicating the UE to ramp uptransmit power, select a different random access resource, or both, andreceiving at a second uplink transmission power, a second random accessresource, or both, the retransmitted random access preamble orconnection request based at least in part on an absence of a response tothe random access preamble or connection request, wherein the seconduplink transmission power is ramped up from the first uplinktransmission power, and wherein the retransmission is in accordance witha maximum retransmission number associated with the random accesspreamble or connection request.

An apparatus for wireless communication is described. The apparatus mayinclude means for receiving, at a first uplink transmission power andover a first random access resource, a random access preambletransmitted from a UE over a first uplink transmission beam, means fortransmitting a random access response message in response to the randomaccess preamble, means for receiving a connection request based at leastin part on the random access response message, means for transmitting,to the UE, a signal indicating the UE to ramp up transmit power, selecta different random access resource, or both, and means for receiving ata second uplink transmission power, a second random access resource, orboth, the retransmitted random access preamble or connection requestbased at least in part on an absence of a response to the random accesspreamble or connection request, wherein the second uplink transmissionpower is ramped up from the first uplink transmission power, and whereinthe retransmission is in accordance with a maximum retransmission numberassociated with the random access preamble or connection request.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to receive, at a first uplinktransmission power and over a first random access resource, a randomaccess preamble transmitted from a UE over a first uplink transmissionbeam, transmit a random access response message in response to therandom access preamble, receive a connection request based at least inpart on the random access response message, transmit, to the UE, asignal indicating the UE to ramp up transmit power, select a differentrandom access resource, or both, and receive at a second uplinktransmission power, a second random access resource, or both, theretransmitted random access preamble or connection request based atleast in part on an absence of a response to the random access preambleor connection request, wherein the second uplink transmission power isramped up from the first uplink transmission power, and wherein theretransmission is in accordance with a maximum retransmission numberassociated with the random access preamble or connection request.

A non-transitory computer-readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to receive, at a first uplinktransmission power and over a first random access resource, a randomaccess preamble transmitted from a UE over a first uplink transmissionbeam, transmit a random access response message in response to therandom access preamble, receive a connection request based at least inpart on the random access response message, transmit, to the UE, asignal indicating the UE to ramp up transmit power, select a differentrandom access resource, or both, and receive at a second uplinktransmission power, a second random access resource, or both, theretransmitted random access preamble or connection request based atleast in part on an absence of a response to the random access preambleor connection request, wherein the second uplink transmission power isramped up from the first uplink transmission power, and wherein theretransmission is in accordance with a maximum retransmission numberassociated with the random access preamble or connection request.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communicationthat supports uplink transmission parameter selection during randomaccess message transmission and retransmission in accordance withaspects of the present disclosure.

FIG. 2 illustrates an example of a system that supports uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with aspects of thepresent disclosure.

FIG. 3 illustrates an example of a synchronization procedure thatsupports uplink transmission parameter selection during random accessmessage transmission and retransmission in accordance with aspects ofthe present disclosure.

FIG. 4 illustrates an example of a process flow that supports uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with aspects of thepresent disclosure.

FIG. 5 illustrates an example of a process flow that supports uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with aspects of thepresent disclosure.

FIGS. 6 through 8 show block diagrams of a device that supports uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with aspects of thepresent disclosure.

FIG. 9 illustrates a block diagram of a system including a userequipment (UE) that supports uplink transmission parameter selectionduring random access message transmission and retransmission inaccordance with aspects of the present disclosure.

FIGS. 10 through 12 show block diagrams of a device that supports uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with aspects of thepresent disclosure.

FIG. 13 illustrates a block diagram of a system including a base stationthat supports uplink transmission parameter selection during randomaccess message transmission and retransmission in accordance withaspects of the present disclosure.

FIGS. 14 through 19 illustrate methods for uplink transmission parameterselection during random access message transmission and retransmissionin accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

In a wireless communications system, such as millimeter wave (mmW) or anew radio (NR) system, a base station and a user equipment (UE) mayutilize directional random access channel (RACH) transmissions during arandom access procedure (e.g., a four-step RACH procedure). The basestation may transmit multiple synchronization signals during asynchronization subframe. For example, the synchronization subframe maycontain a number of symbols (e.g., 14 symbols) and the base station maytransmit a directional synchronization signal in each symbol. Eachdirectional synchronization signal may be transmitted in a differentdirection. The UE may receive one or more directional synchronizationsignals, and may determine a RACH resource and an uplink transmissionbeam for a directional RACH request message transmission, which may betransmitted to gain initial network access. The base station may listenfor signals (e.g., a RACH request message, a random access message, arandom access preamble, a Message 1 (Msg1) transmission) in differentdirections and different time slots and if the base station successfullyreceives a directional RACH request message from a UE, the base stationmay transmit a directional RACH response message (e.g., Message 2(Msg2)) to the UE in response to the RACH request message. In someexamples, if the UE does not receive an appropriate response to thefirst RACH message, the UE may retransmit the first RACH message. Forretransmission, the UE may determine or select different parameters fortransmission of the first RACH message. For instance, the UE may adjustthe transmission power or avoid the symbol or beam that was used duringthe first instance of the first RACH message. For example, the UE mayselect a different transmission power, RACH resource, or beam than thoseused in the previous transmission(s) or retransmission(s).

After receiving the directional RACH response message, the UE maytransmit a second RACH message (e.g., a connection request message, aMessage 3 (Msg3), an L2/L3 message) to the base station. However, insome instances, communication conditions (e.g., estimated path loss,traffic density, location of the UE, signal strengths, channel quality,etc.) may change and the parameters (e.g., transmission power,transmission beam, RACH resource) used for transmission of the initialRACH request message or random access preamble (e.g., Msg1) may not besuitable for transmitting the second RACH message. Thus, the UE maydetermine or select different parameters for transmission of the secondRACH message. For instance, the UE may adjust the transmission power oravoid the symbol or beam that was used during the initial RACH requestmessage. For example, the UE may select a different transmission power,RACH resource, or beam than those used in the previous transmission(s)or previous retransmission(s).

In some examples, if the UE does not receive an appropriate response tothe second RACH message, the UE may retransmit the second RACH message.For retransmission, the UE may again select different parameters forcommunicating the retransmission to the base station. For instance, theUE may select a different transmission power, beam, or RACH resourcethan previously used in the initial RACH request message or in the firsttransmission of the second RACH message or any other previousretransmission(s) (e.g., if the second RACH message is retransmittedmultiple times).

In some cases, the base station may infer that a RACH collision hasoccurred due to the absence of a random access message from the UE, or,may occur due to changing communication conditions. In such cases, thebase station may signal (e.g., using a master information block (MIB),master system information block (MSIB), etc.) the UE to ramp up transmitpower, select different RACH resources during retransmission, or both.

Aspects of the disclosure are initially described in the context of awireless communications system. Aspects of the disclosure are furtherillustrated by and described with reference to apparatus diagrams,system diagrams, and flowcharts that relate to uplink transmissionparameter selection during random access message transmission andretransmission.

FIG. 1 illustrates an example of a wireless communications system 100 inaccordance with various aspects of the present disclosure. The wirelesscommunications system 100 includes base stations 105, UEs 115, and acore network 130. In some examples, the wireless communications system100 may be an LTE (or LTE-Advanced) network, or an NR network. In somecases, wireless communications system 100 may support enhanced broadbandcommunications, ultra-reliable (i.e., mission critical) communications,low latency communications, and communications with low-cost andlow-complexity devices.

Base stations 105 may wirelessly communicate with UEs 115 via one ormore base station antennas. Each base station 105 may providecommunication coverage for a respective geographic coverage area 110.Communication links 125 shown in wireless communications system 100 mayinclude uplink transmissions from a UE 115 to a base station 105, ordownlink transmissions, from a base station 105 to a UE 115. Controlinformation and data may be multiplexed on an uplink channel or downlinkaccording to various techniques. Control information and data may bemultiplexed on a downlink channel, for example, using time divisionmultiplexing (TDM) techniques, frequency division multiplexing (FDM)techniques, or hybrid TDM-FDM techniques. In some examples, the controlinformation transmitted during a transmission time interval (TTI) of adownlink channel may be distributed between different control regions ina cascaded manner (e.g., between a common control region and one or moreUE-specific control regions).

UEs 115 may be dispersed throughout the wireless communications system100, and each UE 115 may be stationary or mobile. A UE 115 may also bereferred to as a mobile station, a subscriber station, a mobile unit, asubscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology. A UE 115 may alsobe a cellular phone, a personal digital assistant (PDA), a wirelessmodem, a wireless communication device, a handheld device, a tabletcomputer, a laptop computer, a cordless phone, a personal electronicdevice, a handheld device, a personal computer, a wireless local loop(WLL) station, an Internet of things (IoT) device, an Internet ofEverything (IoE) device, a machine type communication (MTC) device, anappliance, an automobile, or the like.

In some cases, a UE 115 may also be able to communicate directly withother UEs (e.g., using a peer-to-peer (P2P) or device-to-device (D2D)protocol). One or more of a group of UEs 115 utilizing D2Dcommunications may be within the coverage area 110 of a cell. Other UEs115 in such a group may be outside the coverage area 110 of a cell, orotherwise unable to receive transmissions from a base station 105. Insome cases, groups of UEs 115 communicating via D2D communications mayutilize a one-to-many (1:M) system in which each UE 115 transmits toevery other UE 115 in the group. In some cases, a base station 105facilitates the scheduling of resources for D2D communications. In othercases, D2D communications are carried out independent of a base station105.

Some UEs 115, such as MTC or IoT devices, may be low cost or lowcomplexity devices, and may provide for automated communication betweenmachines, i.e., Machine-to-Machine (M2M) communication. M2M or MTC mayrefer to data communication technologies that allow devices tocommunicate with one another or a base station without humanintervention. For example, M2M or MTC may refer to communications fromdevices that integrate sensors or meters to measure or captureinformation and relay that information to a central server orapplication program that can make use of the information or present theinformation to humans interacting with the program or application. SomeUEs 115 may be designed to collect information or enable automatedbehavior of machines. Examples of applications for MTC devices includesmart metering, inventory monitoring, water level monitoring, equipmentmonitoring, healthcare monitoring, wildlife monitoring, weather andgeological event monitoring, fleet management and tracking, remotesecurity sensing, physical access control, and transaction-basedbusiness charging.

In some cases, an MTC device may operate using half-duplex (one-way)communications at a reduced peak rate. MTC devices may also beconfigured to enter a power saving “deep sleep” mode when not engagingin active communications. In some cases, MTC or IoT devices may bedesigned to support mission critical functions and wirelesscommunications system may be configured to provide ultra-reliablecommunications for these functions.

Base stations 105 may communicate with the core network 130 and with oneanother. For example, base stations 105 may interface with the corenetwork 130 through backhaul links 132 (e.g., S1, etc.). Base stations105 may communicate with one another over backhaul links 134 (e.g., X2,etc.) either directly or indirectly (e.g., through core network 130).Base stations 105 may perform radio configuration and scheduling forcommunication with UEs 115, or may operate under the control of a basestation controller (not shown). In some examples, base stations 105 maybe macro cells, small cells, hot spots, or the like. Base stations 105may also be referred to as eNodeBs (eNBs) 105.

A base station 105 may be connected by an S1 interface to the corenetwork 130. The core network 130 may be an evolved packet core (EPC),which may include at least one mobility management entity (MME), atleast one serving gateway (S-GW), and at least one Packet Data Network(PDN) Gateway (P-GW). The MME may be the control node that processes thesignaling between the UE 115 and the EPC. All user internet protocol(IP) packets may be transferred through the S-GW, which itself may beconnected to the P-GW. The P-GW may provide IP address allocation aswell as other functions. The P-GW may be connected to the networkoperators IP services. The operators IP services may include theInternet, the Intranet, an IP Multimedia Subsystem (IMS), and aPacket-Switched Streaming Service (PSS).

Wireless communications system 100 may operate in an ultra highfrequency (UHF) frequency region using frequency bands from 700 MHz to2600 MHz (2.6 GHz), although in some cases WLAN networks may usefrequencies as high as 4 GHz. This region may also be known as thedecimeter band, since the wavelengths range from approximately onedecimeter to one meter in length. UHF waves may propagate mainly by lineof sight, and may be blocked by buildings and environmental features.However, the waves may penetrate walls sufficiently to provide serviceto UEs 115 located indoors. Transmission of UHF waves is characterizedby smaller antennas and shorter range (e.g., less than 100 km) comparedto transmission using the smaller frequencies (and longer waves) of thehigh frequency (HF) or very high frequency (VHF) portion of thespectrum. In some cases, wireless communications system 100 may alsoutilize extremely high frequency (EHF) portions of the spectrum (e.g.,from 30 GHz to 300 GHz). This region may also be known as the millimeterband, since the wavelengths range from approximately one millimeter toone centimeter in length. Thus, EHF antennas may be even smaller andmore closely spaced than UHF antennas. In some cases, this mayfacilitate use of antenna arrays within a UE 115 (e.g., for directionalbeamforming). However, EHF transmissions may be subject to even greateratmospheric attenuation and shorter range than UHF transmissions.

Thus, wireless communications system 100 may support millimeter wave(mmW) communications between UEs 115 and base stations 105. Devicesoperating in mmW or EHF bands may have multiple antennas to allowbeamforming. That is, a base station 105 may use multiple antennas orantenna arrays to conduct beamforming operations for directionalcommunications with a UE 115. Beamforming (which may also be referred toas spatial filtering or directional transmission) is a signal processingtechnique that may be used at a transmitter (e.g., a base station 105)to shape and/or steer an overall antenna beam in the direction of atarget receiver (e.g., a UE 115). This may be achieved by combiningelements in an antenna array in such a way that transmitted signals atparticular angles experience constructive interference while othersexperience destructive interference.

Multiple-input multiple-output (MIMO) wireless systems use atransmission scheme between a transmitter (e.g., a base station 105) anda receiver (e.g., a UE 115), where both transmitter and receiver areequipped with multiple antennas. Some portions of wirelesscommunications system 100 may use beamforming. For example, base station105 may have an antenna array with a number of rows and columns ofantenna ports that the base station 105 may use for beamforming in itscommunication with UE 115. Signals may be transmitted multiple times indifferent directions (e.g., each transmission may be beamformeddifferently). A mmW receiver (e.g., a UE 115) may try multiple beams(e.g., antenna subarrays) while receiving the synchronization signals.

In some cases, the antennas of a base station 105 or UE 115 may belocated within one or more antenna arrays, which may support beamformingor MIMO operation. One or more base station antennas or antenna arraysmay be collocated at an antenna assembly, such as an antenna tower. Insome cases, antennas or antenna arrays associated with a base station105 may be located in diverse geographic locations. A base station 105may multiple use antennas or antenna arrays to conduct beamformingoperations for directional communications with a UE 115.

In some cases, wireless communications system 100 may be a packet-basednetwork that operates according to a layered protocol stack. In the userplane, communications at the bearer or Packet Data Convergence Protocol(PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may insome cases perform packet segmentation and reassembly to communicateover logical channels. A Medium Access Control (MAC) layer may performpriority handling and multiplexing of logical channels into transportchannels. The MAC layer may also use Hybrid ARQ (HARD) to provideretransmission at the MAC layer to improve link efficiency. In thecontrol plane, the Radio Resource Control (RRC) protocol layer mayprovide establishment, configuration, and maintenance of an RRCconnection between a UE 115 and a network device 105-c, network device105-b, or core network 130 supporting radio bearers for user plane data.At the Physical (PHY) layer, transport channels may be mapped tophysical channels.

Time intervals in LTE or NR may be expressed in multiples of a basictime unit (which may be a sampling period of T_(s)=1/30,720,000seconds). Time resources may be organized according to radio frames oflength of 10 ms (T_(f)=307200 T_(s)), which may be identified by asystem frame number (SFN) ranging from 0 to 1023. Each frame may includeten 1 ms subframes numbered from 0 to 9. A subframe may be furtherdivided into two 0.5 ms slots, each of which contains 6 or 7 modulationsymbol periods (depending on the length of the cyclic prefix prependedto each symbol). Excluding the cyclic prefix, each symbol contains 2048sample periods. In some cases the subframe may be the smallestscheduling unit, also known as a TTI. In other cases, a TTI may beshorter than a subframe or may be dynamically selected (e.g., in shortTTI bursts or in selected component carriers using short TTIs).

A resource element may consist of one symbol period and one subcarrier(e.g., a 15 KHz frequency range). A resource block may contain 12consecutive subcarriers in the frequency domain and, for a normal cyclicprefix in each OFDM symbol, 7 consecutive OFDM symbols in the timedomain (1 slot), or 84 resource elements. The number of bits carried byeach resource element may depend on the modulation scheme (theconfiguration of symbols that may be selected during each symbolperiod). Thus, the more resource blocks that a UE receives and thehigher the modulation scheme, the higher the data rate may be.

In some cases, wireless communications system 100 may utilize enhancedcomponent carriers (eCCs). An eCC may be characterized by one or morefeatures including: wider bandwidth, shorter symbol duration, shorterTTIs, and modified control channel configuration. In some cases, an eCCmay be associated with a carrier aggregation configuration or a dualconnectivity configuration (e.g., when multiple serving cells have asuboptimal or non-ideal backhaul link). An eCC may also be configuredfor use in unlicensed spectrum or shared spectrum (where more than oneoperator is allowed to use the spectrum). An eCC characterized by widebandwidth may include one or more segments that may be utilized by UEs115 that are not capable of monitoring the whole bandwidth or prefer touse a limited bandwidth (e.g., to conserve power).

In some cases, an eCC may utilize a different symbol duration than otherCCs, which may include use of a reduced symbol duration as compared withsymbol durations of the other CCs. A shorter symbol duration may beassociated with increased subcarrier spacing. A TTI in an eCC mayconsist of one or multiple symbols. In some cases, the TTI duration(that is, the number of symbols in a TTI) may be variable. In somecases, an eCC may utilize a different symbol duration than other CCs,which may include use of a reduced symbol duration as compared withsymbol durations of the other CCs. A shorter symbol duration isassociated with increased subcarrier spacing. A device, such as a UE 115or base station 105, utilizing eCCs may transmit wideband signals (e.g.,20, 40, 60, 80 Mhz, etc.) at reduced symbol durations (e.g., 16.67microseconds). A TTI in eCC may consist of one or multiple symbols. Insome cases, the TTI duration (that is, the number of symbols in a TTI)may be variable.

In some cases, wireless system 100 may utilize both licensed andunlicensed radio frequency spectrum bands. For example, wireless system100 may employ LTE License Assisted Access (LTE-LAA) or LTE Unlicensed(LTE-U) radio access technology or NR technology in an unlicensed bandsuch as the 5 GHz Industrial, Scientific, and Medical (ISM) band. Whenoperating in unlicensed radio frequency spectrum bands, wireless devicessuch as base stations 105 and UEs 115 may employ listen-before-talk(LBT) procedures to ensure the channel is clear before transmittingdata. In some cases, operations in unlicensed bands may be based on a CAconfiguration in conjunction with CCs operating in a licensed band.Operations in unlicensed spectrum may include downlink transmissions,uplink transmissions, or both. Duplexing in unlicensed spectrum may bebased on frequency division duplexing (FDD), time division duplexing(TDD) or a combination of both.

In some examples, a UE 115 and a base station 105 may participate in adirectional RACH procedure. For instance, the base station 105 maytransmit synchronization signals in different directions using differenttransmission beams. The UE 115 may receive one or more of thesynchronization signals and select RACH resources for transmission of aninitial random access message based on the reception of thesynchronization signals. In some cases, the UE 115 may transmit theinitial RACH message and receive a RACH response from the base station105.

During reception of the RACH response from the base station 105, the UE115 and the base station 105 may participate in a beam refinementprocedure in which the base station 105 refines its beam (e.g., narrowsa beam width, or selects a beam from one or more beams) used fortransmission of downlink messages to the UE 115. During beam refinement,the UE 115 may receive multiple transmission beams from the base station105 to help the base station 105 determine an appropriate beam to usefor communication with the UE 115. Based on the beam refinementprocedure and/or the RACH response from the base station 105, the UE 115may transmit a second random access message (e.g., connection request)to the base station 105. In some cases, however, using the sameparameters used during transmission of the initial random access messagemay not result in a successful reception by the base station 105. Forexample, transmission conditions such as traffic, channel quality, etc.,may change during the time between the initial random access messagetransmission and the time in which the second random access message isto be transmitted. Thus, prior to sending the second random accessmessage, the UE 115 may modify, select, or otherwise determinetransmission parameters (e.g., transmission power, transmission beam,RACH resource) to use for transmission of the second random accessmessage that are different than those used for transmission of the firstrandom access message.

In some instances, the UE 115 may transmit the second random accessmessage, but may not receive an appropriate response from the basestation 105. Thus, the UE 115 may decide to retransmit the second randomaccess message using different uplink parameters (e.g., RACH resource,transmission power, transmission beam, etc.) in an attempt tosuccessfully reach the base station 105. In some other cases, the basestation 105 may explicitly signal the UE 115 whether to ramp up transmitpower, select different RACH resources, or both.

FIG. 2 illustrates an example of a wireless communications system 200for uplink transmission parameter selection during random access messagetransmission and retransmission. Wireless communications system 200 mayinclude UE 115-a and base station 105-a, which may be examples of thecorresponding devices described with reference to FIG. 1. Base station105-a may serve coverage area 110-a. In some cases, wirelesscommunication system 200 may operate in the mmW spectrum.

In a mmW system, base station 105-a and UE 115-a may utilize directionalRACH transmissions. Base station 105-a may transmit multiplesynchronization signals during a synchronization subframe. For example,the synchronization subframe may include a number of symbols (e.g., 1,8, 14, 20 symbols). Base station 105-a may transmit a directionalsynchronization signal in each symbol. Each directional synchronizationsignal may be transmitted in a different direction and on a differentbeam 205 in order to cover a portion of or all of coverage area 110-a.For example, base station 105-a may transmit a first directionalsynchronization signal over beam 205-a in a first symbol, a seconddirectional synchronization signal over beam 205-b in a second symbol, athird directional synchronization signal over beam 205-c in a thirdsymbol, and a fourth directional synchronization signal over beam 205-din a fourth symbol of a synchronization subframe. It should beunderstood that base station 105-a may transmit any number ofdirectional synchronization signals without departing from the scope ofthe disclosure.

UE 115-a may receive a directional synchronization signal (e.g., overbeam 205-a), and may determine a RACH resource and a beam (e.g., thefirst symbol and beam 205-a) for transmitting an initial random accessmessage, such as a directional RACH request message, or random accesspreamble, to gain access to the network. In some cases, UE 115-a mayreceive multiple directional synchronization signals from base station105-a, and may select one of the synchronization signals to determineuplink resources and an uplink beam for transmission. For example, theselection may be based on a received signal strength (e.g., referencesignal received power (RSRP), received signal strength indication(RSSI), channel quality indicator (CQI), signal to noise ratio (SNR),etc.) of the directional synchronization signal. In some cases, the UE115-a may select a RACH resource or an uplink transmission beamcorresponding to the synchronization signal with the greatest RSSI orRSRP, among others.

Base station 105-a may listen for signals in different directions anddifferent time slots, and if the base station 105-a receives adirectional RACH request message, or random access preamble from UE115-a, the base station 105-a may transmit a directional RACH responsemessage to UE 115-a in response to the directional RACH request message.The RACH response message may be transmitted on a downlink sharedchannel (DL-SCH) and may include a temporary identifier, an uplink grantresource, a transmission power control (TPC) command, or otherinformation for the UE 115-a.

Following reception of a directional RACH response message, the UE 115-amay transmit a second random access message (e.g., a connection request)to the base station 105-a. In some cases, the second random accessmessage may also be referred to as a Layer 2 (L2) or Layer 3 (L3)message, and may be a Msg3 of a four part random access procedure, anRRC connection request message, a tracking area update, or a schedulingrequest (SR). In some cases, the base station 105-a may refine itstransmit beam 205 for transmission of the directional RACH responsemessage, based on for example, channel conditions at the time. The basestation 105-a may utilize a narrow beam pattern, or increase itstransmit power, or vary other beam-related parameters. The beamrefinement procedure may be initiated by the base station 105-a duringtransmission of the directional RACH response message and may be used bythe UE 115-a in selecting a different uplink transmit power or adifferent uplink transmit beam during transmission of the second randomaccess message, as described below.

In some cases, the UE 115-a may transmit the second random accessmessage using parameters different than those used during transmissionof the initial random access message. For instance, the quality of thechannel or the beam may have changed after transmitting the initialrandom access message and the UE 115-a may decide that using the sametransmission parameters may not result in a successful transmission ofthe second random access message. In another example, the UE 115-a mayhave moved to a different location and the previously determinedtransmission parameter are no longer suitable for a successfultransmission. Additionally or alternatively, after transmitting thesecond random access message, the base station 105-a may notsuccessfully receive the second random access message. For instance ifthe UE 115-a does not receive an appropriate response from the basestation 105-a (e.g., within a predetermined amount of time), the UE115-a may decide to retransmit the second random access message and mayselect different transmission parameter(s) than those used in theinitial random access message transmission or in previous transmissionof the second random access message (e.g., if the second random accessmessage is retransmitted multiple times). In any case, the UE 115-a mayselect a different transmission power, select a different RACH resource,or use a different uplink transmission beam during the retransmission ofthe second random access message, as compared to the parameters used inprevious transmission(s) of the second random access message or in thetransmission of the initial random access message. For instance, the UE115-a may select a second uplink transmission power based in part on apath loss associated with the random access procedure, and retransmitthe second random access message (or connection request) using an uplinktransmission beam different from the uplink transmission for theprevious transmission.

In some examples, the resources used for transmission of the secondrandom access message (or retransmission of the second random accessmessage) may be different than the resources used for transmission ofthe initial random access message or the resources used in a previoustransmission of the second random access message. For example, thesecond random access message may be transmitted using resourcesorthogonal to resources that are reserved or allocated for the initialrandom access message. In some cases, the base station 105-a maytransmit information to the UE 115-a about the resources used for RACHcommunications. For instance, the base station 105-a may transmitinformation indicating the resources reserved for transmission of theinitial random access message, the second random access message,retransmission of any preceding random access message, or the like. Insome examples, the base station 105-a may allocate resources for theinitial random access message based on one or more downlinksynchronization signals. For instance, the base station 105-a maydetermine a mapping between synchronization signals and resources forinitial random access messages or for the second random access messageand may transmit information relating to the mapping to the UE 115-a.

In some cases, the UE 115-a may the select the transmit power based on,for example, a TPC command received in the directional RACH responsemessage from the base station 105-a. The transmission power obtainedfrom the TPC command may be adjusted based on a path loss estimated fromone or more beams 205 (e.g., received by the UE 115-a duringsynchronization) or from the beams used during a beam refinementprocedure.

In some cases, the UE 115-a may select a transmission power fortransmission or retransmission of the second random access messagewithout an indication from the base station 105-a. For instance, the UE115-a may determine a path loss estimate from a downlink transmit beam205 used to transmit the RACH response message and adjust the transmitpower for the second random access message based on the path lossestimate. In some cases, the UE 115-a may ramp up transmission power orchange the transmission beam during one or more subsequentretransmissions (e.g., based on the path loss estimate). In such cases,the UE 115-a may maintain a count of the retransmission numberassociated with the second random access message, and may base furthertransmission parameters off of the retransmission number. For example,the transmission power may be based on a retransmission numberassociated with the second random access message (e.g., the greater theretransmission number, the greater the transmission power used). Theretransmission number may be used in combination with path lossestimates (e.g., path loss estimates associated with one or moredownlink synchronization beams or beams used during beam refinement orMsg2 transmission, etc.).

According to some aspects, the UE 115-a may determine a path lossestimate from the downlink transmit beam 205 in the RACH responsemessage and a delta power based on a retransmission number for thesecond random access message. In some cases, the network or the basestation 105-a may specify to the UE 115-a the maximum number ofretransmissions. For example, the base station 105-a may indicate themaximum number of retransmissions over a particular transmission beam,resources, or using a particular transmission power, for the secondrandom access message, using a Master Information Block (MIB), SystemInformation Block (SIB), a Physical Broadcast Channel (PBCH), extendedPBCH, Physical Downlink Shared Channel (PDSCH), or a Physical DownlinkControl Channel (PDCCH). The UE 115-a may then select a transmissionpower based on a combination of the path loss estimate and the deltapower. In some cases, the delta power may be zero or may have a valuebased on whether the difference in path loss between a previoustransmission and a previous reception exceeds a threshold.

In some cases, the base station 105-a may also define the retransmissionprocess for the second random access message, or connection request, ina hierarchical manner. For example, the base station 105-a may definethe maximum number of retransmissions permissible for a given uplinktransmission beam or the total number of uplink transmission beamtrials. In such cases, the UE 115-a may select a different uplinktransmission power for each selected uplink transmission beam, and mayswitch beams in the event that a previously selected UL transmit beam isdeemed unsuccessful.

In some cases, following a beam refinement procedure, the UE 115-a maypredict that the second random access message transmission to the basestation 105-a will be unsuccessful (e.g., based on changes in channelconditions or UE movement). The UE 115-a may then transmit or retransmitthe second random access message in a resource (e.g., a subframe)allocated for the initial or first random access message (e.g, Msg1).For example, the base station 105-a may split resources (e.g.,subcarriers or timeslots) in the subframe allocated for the initialrandom access message and allocate some resources for the second randomaccess message. This technique of transmitting the second random accessmessage on resources dedicated for the first random access message mayenable the UE 115-a to convey to the base station 105-a that channelconditions have deviated from the original downlink synchronizationsignals.

In other examples, the base station 105-a may not split resources in thesubframe allocated for the first random access message and the UE 115-amay autonomously select another different subframe for transmitting thesecond random access message upon unsuccessful receipt of a response.This may reduce the overhead as compared to splitting resources, but maybe associated with an increased probability of collision.

In some examples, the UE 115-a may attempt one or more combinations oftransmission options for retransmission of the first random accessmessage or the second random access message. For example, duringretransmission of a random access message such as a RACH Msg1 preamble,the UE 115-a may attempt ramping the transmission power, selectingdifferent RACH resources (e.g., RACH resource blocks, or selecting adifferent transmission time, etc.), utilizing a different transmit beam,or any combination thereof.

In some cases, the likelihood of the UE 115-a changing its transmit beamduring retransmission of the RACH Msg1 may depend on a beamcorrespondence scenario. In some cases, beam correspondence may refer toa level of conformity between downlink beams from the base station, anduplink transmission beams from the UE. For instance, transmissionreception beam correspondence at a UE may be considered to be satisfiedif the UE determines an appropriate uplink transmission beam, based inpart on downlink measurements on one or more received beams. Forexample, if the UE 115-a has beam correspondence, the UE 115-a mayretransmit RACH Msg1 using the original transmit beam. In some othercases, the UE 115-a may retransmit the RACH Msg1 with a differenttransmit beam. In some examples, the base station 105-a or network maynot be aware of the level of beam correspondence for the UE 115-a inadvance. In such cases, the selection of the transmit beam duringretransmission of the RACH Msg1 may be left to the discretion of the UE115-a.

In some cases, the UE 115-a may not select a different RACH resourcewhile retransmitting the RACH Msg1 preamble. In such cases, two or moreRACH blocks may be combined in a non-coherent manner, which may allowfor an increased probability of RACH detection.

In some other cases, the UE 115-a may estimate or detect that theprobability of a RACH collision exceeds a threshold (e.g., in a denseRACH scenario). In such cases, the UE 115-a may select different PRACHresources during transmission, instead of ramping transmit power. Insome other cases, the base station 105-a may determine the status of aPRACH collision, and may subsequently signal the UE 115-a to ramp uptransmit power, or select a different RACH resource duringretransmission, or a combination.

In some cases, for example in a multi-beam scenario, the UE 115-a mayselect its transmit beam during retransmission of the RACH Msg1.Additionally, in a multi-beam scenario, a base station 105 (e.g., aneNB, or gNB) may signal a UE 115 whether to ramp up transmit power,select a different RACH resource during retransmission, or both. In somecases, the signaling from the base station 105 may be a MIB, a MSIB, orany other downlink message.

FIG. 3 illustrates an example of a synchronization procedure 300 foruplink transmission parameter selection during random access messagetransmission and retransmission. The synchronization procedure 300 mayinclude synchronization subframes 305 (e.g., synchronization subframes305-a, 305-b, and 305-c) and RACH subframes 310. Both types of subframesmay include one or more symbols 315. The synchronization procedure 300may be performed by a UE 115 receiving signals from a base station 105,such as the corresponding devices described with reference to FIGS. 1and 2.

In some cases, the base station 105 may transmit multiple directionalsynchronization signals during synchronization subframe 305-a. Forexample, the base station 105 may transmit a directional synchronizationsignal during each symbol 315-a of synchronization subframe 305-a. Eachdirectional synchronization signal may be transmitted over a differentbeam in a different direction. For example, synchronization subframe305-a may contain fourteen symbols 315. The base station 105 may dividea coverage area (or a portion of a coverage area) into fourteen sectionsand transmit directional synchronization signals on separate beamspointing in each section.

The UE 115 may receive one or more directional synchronization signalsfrom the base station 105, and may select one of the multipledirectional synchronization signals. For example, the UE 115 may selectthe directional synchronization signal with the greatest received signalstrength (e.g., RSSI, RSRP, CQI, etc.). The UE 115 may identify thesymbol (e.g., symbol 325) and the corresponding beam over which the UE115 received the selected directional synchronization signal. In somecases, the UE 115 may randomly select a subcarrier region from thesubcarrier frequencies 320. The UE 115 may transmit a directional RACHrequest message to the base station 105 in RACH resource 330, during theidentified symbol 325 and over the selected subcarrier region.

The base station 105 may receive the directional RACH request messageduring the RACH subframe 310. In response, the base station 105 maytransmit a directional RACH response message to the UE 115. In somecases, the UE 115 and base station 105 may participate in a beamrefinement procedure during transmission of the directional RACHresponse message, and the base station 105 may refine its transmit beamfor transmission of the directional RACH response message (e.g., basedon channel conditions). The base station 105 may utilize a narrow beampattern, increase its transmit power, or select other beam parameters toachieve a higher SNR, RSSI, RSRP, etc. In other examples, the beamrefinement procedure initiated by the base station 105 duringtransmission of the directional RACH response message may trigger the UE115 to select a different uplink transmit power, a different uplinktransmit beam, or a combination thereof, during transmission of thesecond random access message (e.g., Msg3). For instance, if the channelconditions changed, the UE 115 may detect the changes during the beamrefinement procedure and determine that different transmissionparameters may be used for transmission of the second random accessmessage.

The UE 115 may then transmit a second random access message (e.g.,Msg3), which may be transmitted using parameters different from thoseused during transmission of the initial random access message. In somecases, the UE 115 may not receive an appropriate response to Msg3 fromthe base station. For instance, the base station 105 may not havereceived the Msg3. In another example, the Msg3 or the response messagefrom the base station (e.g., Msg4) may have been interfered with. Thus,the UE 115 may retransmit Msg3 to the base station 105 and may selectdifferent parameters for the retransmission. For example, the UE 115 mayselect a different symbol 315, a different subcarrier frequency 320, ora combination of the two, in order to retransmit the directional RACHmessage. For example, the UE 115 may have received a second directionalsynchronization signal during a different symbol than symbol 325. The UE115 may select the different symbol, and the corresponding differentbeam, to retransmit the directional RACH request message to the basestation 105. In some cases, the UE 115 may identify a second uplinktransmission beam for retransmission of Msg 3, which may be differentfrom a first uplink transmission beam used for the first transmission ofMsg3. Further, the UE 115 may select a second uplink transmission powerbased on a path loss associated with the random access procedure, andthe identified second uplink transmission beam. In such cases, the UE115 may retransmit Msg3 based at least in part on the second uplinktransmission power and the second uplink transmission beam.

In some other cases, the base station 105 may separately infer that aRACH collision has occurred due to the absence of the Msg3 from the UE115. In such cases, the base station 105 may signal (e.g., using a MIBor MSIB) the UE to ramp up transmit power, select different RACHresources during retransmission, or both. Further, in some cases, the UE115 may retransmit the Msg3 (or connection request) based in part onreceiving a retransmission grant from the base station 105.

FIG. 4 illustrates an example of a process flow 400 for uplinktransmission parameter selection during random access messagetransmission and retransmission. The process illustrated by process flow400 may be implemented by a UE 115-b and a base station 105-b, which maybe examples of a UE 115 and base station 105 described with reference toFIGS. 1 and 2. In some examples, the process illustrated by flow diagram400 may be implemented in a wireless system operating in mmW spectrum.

At 405, UE 115-b may receive one or more downlink synchronizationsignals from base station 105-b. The base station 105-b may transmitmultiple directional synchronization signals during a downlinksynchronization subframe. For example, the base station 105-b maytransmit a directional synchronization signal during each symbol of thedownlink synchronization subframe. Each directional synchronizationsignal may be transmitted over a different beam in a differentdirection.

At 410, UE 115-b may select one or more parameters for a random accessprocedure based on one or more of the directional synchronizationsignals. For example, the UE 115-b may select the directionalsynchronization signal with the greatest received signal strength (e.g.,RSSI, RSRP, CQI, etc.) and the UE 115-b may identify the symbol and thecorresponding beam over which the selected directional synchronizationsignal was received. In some cases, the UE 115-b may randomly select asubcarrier region comprising one or more subcarriers.

At 415, a random access procedure may be initiated between UE 115-b andbase station 105-b. The UE 115-b may transmit a directional RACH requestmessage or a first random access message (e.g., Msg1) to the basestation 105-b corresponding to the symbol and subcarrier regionidentified at step 410.

At 420, a beam refinement procedure may be initiated between basestation 105-b and UE 115-b as described with reference to FIGS. 2 and 3.In some cases, the base station 105-b may transmit multiple referencesignals (e.g., PSS, SSS, BRS, etc.) over multiple beams in differentdirections. During beam refinement, the base station 105-b may vary itsbeam pattern (e.g., using a narrower beam), or increase its transmitpower, or vary other beam-related parameters. In some cases, the UE115-b may use a plurality of receiving beams oriented in differentdirections to receive the beams transmitted from the base station 105-b.During the beam refinement procedure, the base station 105-b maytransmit a RACH response (e.g., Msg2) over multiple transmission beamsto the UE 115-b, and the UE 115-b may utilize different reception beamsto find a more refined reception beam.

In some cases, the UE 115-b may refine its transmission and receptionbeams based on one or more synchronization signals transmitted from thebase station 105-b. For instance, the base station 105-b may transmitone or more synchronization signals, which may be used by the UE 115-bto refine a reception beam. The UE 115-b then determines an uplinktransmission beam based on the refined reception beam.

At 425, the beam refinement procedure initiated by the base station105-b at 420 may be used by the UE 115-b to select a different uplinktransmit power, a different uplink transmit beam, or a combination ofthe two. The selected parameters may be used during transmission of thesecond random access message (e.g., Msg3, or connection requestmessage).

FIG. 5 illustrates an example of a process flow 500 for uplinktransmission parameter selection during random access messagetransmission and retransmission. The process illustrated by process flow500 may be implemented by a UE 115-c and a base station 105-c, which maybe examples of a UE 115 and base station 105 described with reference toFIGS. 1, 2, and 4. In some examples, the process illustrated by flowdiagram 500 may be implemented in a wireless system operating in mmWspectrum.

At 505, UE 115-c may receive one or more downlink synchronizationsignals from base station 105-c. The base station 105-c may transmitmultiple directional synchronization signals during a downlinksynchronization subframe. For example, the base station 105-c maytransmit a directional synchronization signal during each symbol of thedownlink synchronization subframe. Each directional synchronizationsignal may be transmitted over a different beam in a differentdirection.

At 510, UE 115-c may select one or more parameters for a random accessprocedure based on one or more of the directional synchronizationsignals. For example, the UE 115-c may select the directionalsynchronization signal with the greatest received signal strength andthe UE 115-c may identify the symbol and the corresponding beam overwhich the selected directional synchronization signal was received. Insome cases, the UE 115-c may randomly select a subcarrier regioncomprising one or more subcarriers.

At 515, the UE 115-c may transmit a directional RACH request message ora first random access message to the base station 105-c corresponding tothe symbol and subcarrier region identified at step 510.

At 520, a beam refinement procedure may be initiated between basestation 105-c and UE 115-c as described with reference to FIGS. 2, 3,and 4. The base station 105-c may refine its transmit beam fortransmission of the directional RACH response message (e.g., Msg2) basedon the beam refinement procedure. The base station 105-c may utilize anarrow beam pattern, increase its transmit power, or vary otherbeam-related parameters for transmission of the random access responsemessage at 525. In some cases, the base station 105-c and UE 115-c mayestablish refined transmit and receive beams following transmission ofthe random access response message. Additionally or alternatively, theUE 115-c may refine its transmission and reception beams based on one ormore synchronization signals transmitted from the base station 105-c.For instance, the base station 105-c may transmit one or moresynchronization signals which may be used by the UE 115-c to find afiner reception beam. The UE 115-c may then determine an uplinktransmission beam based on the refined reception beam.

At 530, the UE 115-c may transmit a second random access message to thebase station 105-c in response to the random access response messagetransmitted by the base station 105-c at 525, and based in part on thebeam refinement procedure performed at 520. The second random accessmessage may be an RRC connection request message, an L2/L3 message, or aMsg3, for example.

In some other cases, the UE 115-c may not receive a random accessresponse message from the base station 105-c due to an unsuccessfultransmission of the first random access message at 515. In some othercases, the base station 105-c may deduce that the transmission of itsrandom access response message at 525 was unsuccessful, or, a collisionhas occurred during transmission of the second random access messagefrom the UE 115-c, for example, due to the absence of the second randomaccess message from the UE 115-c. In such cases, at 535, the basestation 105-c may signal (e.g., using a MIB or MSIB) the UE 115-c toramp up transmit power or select different RACH resources duringretransmission of the first random access message or the second randomaccess message.

At 540, the UE 115-c may not have received an appropriate response fromthe base station 105-c, or may have determined that the transmission ofthe first or second random access message was unsuccessful. Thus, the UE115-c may select or adjust one or more uplink transmission parameters.For instance, the UE 115-c may adjust the transmission power, uplinkbeam, or resource used during transmission of the second random accessmessage at 530, or the first random access message at 515. In some othercases, the UE 115-c may adjust the transmission parameters by ramping uptransmit power or selecting different RACH resources for retransmission,based in part on the signaling received from the base station 105-c at535.

Based on the adjusted transmission parameters, the UE 115-c mayretransmit the first or the second random access message at 545. The UE115-c may retransmit the first or the second random access messagemultiple times based on a maximum retransmission number. The UE 115-cmay also retransmit the first or the second random access message withdifferent uplink parameters in each retransmission. In some cases, theUE 115-c may determine a path loss estimate for one or more previoustransmissions and may use the path loss to determine the transmissionpower. The transmission power may also be determined based on a deltapower function dependent on the retransmission number. Further, the UE115-c may identify a different uplink transmission beam and/or power foreach retransmission of the second random access message. In some cases,the UE 115-c may proceed to retransmit the second random access message(or connection request) based at least in part on the identified uplinktransmission beam and power.

At 550, the UE 115-c may receive, from base station 105-c, a response tothe second random access message, such as a Msg4 transmission message ora contention resolution message.

FIG. 6 shows a block diagram 600 of a wireless device 605 that supportsuplink transmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. Wireless device 605 may be an example of aspectsof a UE 115 as described with reference to FIG. 1. Wireless device 605may include receiver 610, UE random access manager 615, and transmitter620. Wireless device 605 may also include a processor. Each of thesecomponents may be in communication with one another (e.g., via one ormore buses).

Receiver 610 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to uplinktransmission parameter selection during random access messagetransmission and retransmission, etc.). Information may be passed on toother components of the device. The receiver 610 may be an example ofaspects of the transceiver 935 described with reference to FIG. 9.

UE random access manager 615 may be an example of aspects of the UErandom access manager 915 described with reference to FIG. 9.

UE random access manager 615 and/or at least some of its varioussub-components may be implemented in hardware, software executed by aprocessor, firmware, or any combination thereof. If implemented insoftware executed by a processor, the functions of the UE random accessmanager 615 and/or at least some of its various sub-components may beexecuted by a general-purpose processor, a digital signal processor(DSP), an application-specific integrated circuit (ASIC), anfield-programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described in thepresent disclosure.

The UE random access manager 615 and/or at least some of its varioussub-components may be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations by one or more physical devices. In someexamples, UE random access manager 615 and/or at least some of itsvarious sub-components may be a separate and distinct component inaccordance with various aspects of the present disclosure. In otherexamples, UE random access manager 615 and/or at least some of itsvarious sub-components may be combined with one or more other hardwarecomponents, including but not limited to an I/O component, atransceiver, a network server, another computing device, one or moreother components described in the present disclosure, or a combinationthereof in accordance with various aspects of the present disclosure.

UE random access manager 615 may identify a first uplink transmissionbeam for a random access procedure, transmit, at a first uplinktransmission power, a random access preamble based on the first uplinktransmission beam. The UE random access manager 615 may receive a randomaccess response message transmitted from a base station in response tothe random access preamble, identify a second uplink transmission beam,select a second uplink transmission power based on a path lossassociated with the random access procedure and the identified seconduplink transmission beam, and transmit, to the base station, aconnection request based on the second uplink transmission power. The UErandom access manager 615 may also transmit, at a first uplinktransmission power, a first random access message or random accesspreamble using a first uplink transmission beam, and receive a randomaccess response message transmitted from a base station in response tothe first random access message.

In some cases, the UE random access manager 615 may transmit, to thebase station, a connection request based on the random access responsemessage, and retransmit the connection request based on an absence of aresponse to the connection request and in accordance with a maximumretransmission number associated with the second random access message.In some cases, UE random access manager 615 may retransmit theconnection request based in part on receiving a retransmission grantfrom the base station.

The UE random access manager 615 may also identify a subframe allocatedfor transmission of a random access preamble, transmit, to a basestation, the random access preamble based on the subframe allocated fortransmission of the first random access message. In some examples, theUE random access manager 615 may receive a random access responsemessage transmitted by the base station in response to the random accesspreamble, and transmit, in the subframe allocated for the random accesspreamble, a connection request message. The UE random access manager 615may transmit, to a base station, a random access preamble using a firstset of resources allocated for transmission of the random accesspreamble, receive a random access response message transmitted by thebase station in response to the random access preamble, determine asecond set of resources for transmission of a connection requestmessage, and transmit, using the second set of resources, the connectionrequest message in response to the random access response message.

Transmitter 620 may transmit signals generated by other components ofthe device. In some examples, the transmitter 620 may be collocated witha receiver 610 in a transceiver module. For example, the transmitter 620may be an example of aspects of the transceiver 935 described withreference to FIG. 9. The transmitter 620 may include a single antenna,or it may include a set of antennas.

FIG. 7 shows a block diagram 700 of a wireless device 705 that supportsuplink transmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. Wireless device 705 may be an example of aspectsof a wireless device 605 or a UE 115 as described with reference toFIGS. 1 and 6. Wireless device 705 may include receiver 710, UE randomaccess manager 715, and transmitter 720. Wireless device 705 may alsoinclude a processor. Each of these components may be in communicationwith one another (e.g., via one or more buses).

Receiver 710 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to uplinktransmission parameter selection during random access messagetransmission and retransmission, etc.). Information may be passed on toother components of the device. The receiver 710 may be an example ofaspects of the transceiver 935 described with reference to FIG. 9.

UE random access manager 715 may be an example of aspects of the UErandom access manager 915 described with reference to FIG. 9.

UE random access manager 715 may also include transmission beamidentifier 725, random access transmitter 730, random access receiver735, transmission power component 740, retransmission component 745, andsubframe identifier 750.

Transmission beam identifier 725 may identify a first uplinktransmission beam for a random access procedure.

Random access transmitter 730 may transmit, at a first uplinktransmission power, a first random access message (or random accesspreamble) based on the first uplink transmission beam, transmit, to thebase station, a second random access message (or connection request)based on the second uplink transmission power. In some cases,transmitting the second random access message includes transmitting thesecond random access message in a subframe allocated for transmission ofthe first random access message or using a second uplink transmissionresource different from a first uplink transmission resource utilizedfor transmission of the first random access message.

In some examples, the random access transmitter 730 may transmit, at afirst uplink transmission power, a first random access message using afirst uplink transmission beam, transmit, to the base station, a secondrandom access message based on the random access response message, andtransmit, to a base station, the first random access message based onthe subframe allocated for transmission of the first random accessmessage. The random access transmitter 730 may transmit, in the subframeallocated for the first random access message, a second random accessmessage. In some cases, transmitting the second random access messagemay be based on reception of one or more multiple synchronizationsignals. The random access transmitter 730 may transmit, to a basestation, a first random access message using a first set of resourcesallocated for transmission of the first random access message, andtransmit, using the second set of resources, the second random accessmessage in response to the random access response message.

Random access receiver 735 may receive a random access response messagetransmitted from a base station in response to the first random accessmessage, and receive, from the base station, a maximum retransmissionnumber, where retransmitting the second random access message is basedon the maximum retransmission number. In some cases, the random accessreceiver 735 may receive, from the base station, an indication of one ormore uplink transmit parameters for retransmitting the first randomaccess or the second random access message, wherein the indication maysignal the UE to ramp up its uplink transmit power, utilize differenttransmission resources, or both.

The random access receiver 735 may receive, from the base station, themaximum retransmission number associated with the second random accessmessage, and receive a random access response message transmitted by thebase station in response to the first random access message. In somecases, the maximum retransmission number is associated with at least oneof a total number of retransmission attempts of the second random accessmessage or a maximum number of retransmission attempts of the secondrandom access message for each of a set of uplink transmission powers.In some examples, the maximum retransmission number is associated withat least one of a total number of retransmission attempts of the secondrandom access message, a maximum number of retransmission attempts ofthe second random access message for each of a set of uplinktransmission powers, a maximum number of retransmission attempts of thesecond random access message for each of a set of uplink transmissionbeams, or any combination thereof. Random access receiver 735 mayreceive a random access response message transmitted by the base stationin response to the first random access message.

Transmission power component 740 may select a second uplink transmissionpower based on a path loss associated with the random access procedureand selecting the second uplink transmission power may be based on atransmission power conveyed in the random access response message. Thetransmission power component 740 may select the second uplinktransmission power by adjusting the transmission power conveyed in therandom access response message based on the path loss, and in somecases, selecting the second uplink transmission power may be based on aretransmission number of the second random access message. In someexamples, the second uplink transmission power is different from thefirst uplink transmission power. In some cases, the transmission powercomponent 740 may select a third uplink transmission power forretransmission of the second random access message, based on anindication received from the base station. In some examples, the thirduplink transmission power may be different from both the second uplinktransmission power (e.g., ramp-up of the second uplink transmissionpower), and the first uplink transmission power.

Retransmission component 745 may retransmit the second random accessmessage (or connection request) based on the second uplink transmissionbeam and retransmit the second random access message based on an absenceof a response to the second random access message, and in accordancewith a maximum retransmission number associated with the second randomaccess message.

Subframe identifier 750 may identify a subframe allocated fortransmission of a first random access message. In some cases, subframeidentifier 750 may also determine a second set of resources fortransmission of a second random access message.

Transmitter 720 may transmit signals generated by other components ofthe device. In some examples, the transmitter 720 may be collocated witha receiver 710 in a transceiver module. For example, the transmitter 720may be an example of aspects of the transceiver 935 described withreference to FIG. 9. The transmitter 720 may include a single antenna,or it may include a set of antennas.

FIG. 8 shows a block diagram 800 of a UE random access manager 815 thatsupports uplink transmission parameter selection during random accessmessage transmission and retransmission in accordance with variousaspects of the present disclosure. The UE random access manager 815 maybe an example of aspects of a UE random access manager 615, a UE randomaccess manager 715, or a UE random access manager 915 described withreference to FIGS. 6, 7, and 9. The UE random access manager 815 mayinclude transmission beam identifier 820, random access transmitter 825,random access receiver 830, transmission power component 835,retransmission component 840, subframe identifier 845, beam refinementcomponent 850, synchronization component 855, path loss component 860,resource component 865, and transmission beam selector 870. Each ofthese modules may communicate, directly or indirectly, with one another(e.g., via one or more buses).

Transmission beam identifier 820 may identify a first uplinktransmission beam for a random access procedure.

Random access transmitter 825 may transmit, at a first uplinktransmission power, a first random access message (e.g., random accesspreamble) based on the first uplink transmission beam and transmit, tothe base station, a second random access message (e.g., connectionrequest) based on the second uplink transmission power and a randomaccess response message received from the base station. In someexamples, transmitting the connection request includes transmitting theconnection request in a subframe allocated for transmission of therandom access preamble. The random access transmitter 825 may transmitthe connection request using a second uplink transmission resource.

In some cases, the random access transmitter 825 may transmit, to a basestation, the first random access message based on the subframe allocatedfor transmission of the first random access message. The random accesstransmitter 825 may transmit, in the subframe allocated for the firstrandom access message, a second random access message, wheretransmitting the second random access message is based on reception ofone or more of the multiple synchronization signals.

Random access receiver 830 may receive a random access response messagetransmitted from a base station in response to the first random accessmessage and receive, from the base station, a maximum retransmissionnumber, where retransmitting the second random access message is basedon the maximum retransmission number. In some cases, the random accessreceiver 830 may receive, from the base station, the maximumretransmission number associated with the second random access message,and receive a random access response message transmitted by the basestation in response to the first random access message. In some cases,the random access receiver 830 may further receive, from the basestation, an indication or signal to ramp up transmit power, utilizedifferent transmission resources, or both, for retransmission of thefirst or the second random access message.

In some examples, the maximum retransmission number is associated withat least one of a total number of retransmission attempts of the secondrandom access message or a maximum number of retransmission attempts ofthe second random access message for each of a set of uplinktransmission powers. In some cases, the maximum retransmission number isassociated with at least one of a total number of retransmissionattempts of the second random access message, a maximum number ofretransmission attempts of the second random access message for each ofa set of uplink transmission powers, a maximum number of retransmissionattempts of the second random access message for each of a set of uplinktransmission beams, or any combination thereof.

Transmission power component 835 may select a second uplink transmissionpower based on a path loss associated with the random access procedure,and select the second uplink transmission power based on a transmissionpower conveyed in the random access response message. In some examples,selecting the second uplink transmission power includes adjusting thetransmission power conveyed in the random access response message basedon the path loss, and selecting the second uplink transmission power isbased on a retransmission number of the second random access message. Insome cases, the second uplink transmission power is different from thefirst uplink transmission power. In some cases, the transmission powercomponent 835 may select a third uplink transmission power or ramp upthe first or second uplink transmission powers for retransmission of oneof the first or second random access message, based on an indicationreceived from the base station. In some examples, the third uplinktransmission power may be different from the first and second uplinktransmission powers.

Retransmission component 840 may retransmit the second random accessmessage based on the second uplink transmission beam, on an absence of aresponse to the second random access message, and in accordance with amaximum retransmission number associated with the second random accessmessage.

Subframe identifier 845 may identify a subframe allocated fortransmission of a first random access message. Subframe identifier 845may determine a second set of resources for transmission of a secondrandom access message. In some cases, the second set of resources may bea subset of the first set of resources.

Beam refinement component 850 may participate in a beam refinementprocess during reception of the random access response message, wherethe path loss associated with the random access procedure is determinedbased on the beam refinement process.

Synchronization component 855 may receive, from the base station,multiple synchronization signals (e.g., PSS, SSS, NR-PSS, NR-SSS, etc.),where the path loss associated with the random access procedure isdetermined based on at least one of the multiple synchronizationsignals. The synchronization component 855 may also receive, from thebase station, multiple synchronization signals, where identifying thefirst uplink transmission beam for the first random access message isbased on reception of one or more of the multiple synchronizationsignals, and receive multiple synchronization signals from the basestation, where identifying the subframe allocated for transmission ofthe first random access message is based on reception of one or more ofthe multiple synchronization signals. Synchronization component 855 mayreceive multiple synchronization signals from the base station, wherethe first set of resources or the second set of resources is determinedbased at least in part on reception of one or more of the multiplesynchronization signals. In some examples, the second set of resourcesis determined based at least in part on a signal quality (e.g., RSRP,RSRQ, CQI, etc.) of one or more of the multiple synchronization signals.

Path loss component 860 may select the second uplink transmission power.In some cases, the selected second uplink transmission power is furtherbased on a difference between a path loss associated with the randomaccess response message and a path loss associated with transmission ofthe first random access message.

Resource component 865 may receive, from the base station, an indicationof one or more resources for transmission of the second random accessmessage, identify, autonomously, one or more resources for transmissionof the second random access message, identify a first uplinktransmission resource for transmission of the first random accessmessage, and select, based on the random access response message or theindication, a second uplink transmission resource different from thefirst uplink transmission resource for transmission of the second randomaccess message.

Transmission beam selector 870 may select a second uplink transmissionbeam different than the first uplink transmission beam.

FIG. 9 shows a diagram of a system 900 including a device 905 thatsupports uplink transmission parameter selection during random accessmessage transmission and retransmission in accordance with variousaspects of the present disclosure. Device 905 may be an example of orinclude the components of wireless device 605, wireless device 705, or aUE 115 as described above, e.g., with reference to FIGS. 1, 6 and 7.Device 905 may include components for bi-directional voice and datacommunications including components for transmitting and receivingcommunications, including UE random access manager 915, processor 920,memory 925, software 930, transceiver 935, antenna 940, and I/Ocontroller 945. These components may be in electronic communication viaone or more busses (e.g., bus 910). Device 905 may communicatewirelessly with one or more base stations 105.

Processor 920 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a central processing unit (CPU), amicrocontroller, an ASIC, an FPGA, a programmable logic device, adiscrete gate or transistor logic component, a discrete hardwarecomponent, or any combination thereof). In some cases, processor 920 maybe configured to operate a memory array using a memory controller. Inother cases, a memory controller may be integrated into processor 920.Processor 920 may be configured to execute computer-readableinstructions stored in a memory to perform various functions (e.g.,functions or tasks supporting uplink transmission parameter selectionduring random access message transmission and retransmission).

Memory 925 may include random access memory (RAM) and read only memory(ROM). The memory 925 may store computer-readable, computer-executablesoftware 930 including instructions that, when executed, cause theprocessor to perform various functions described herein. In some cases,the memory 925 may contain, among other things, a basic input/outputsystem (BIOS) which may control basic hardware and/or software operationsuch as the interaction with peripheral components or devices.

Software 930 may include code to implement aspects of the presentdisclosure, including code to support uplink transmission parameterselection during random access message transmission and retransmission.Software 930 may be stored in a non-transitory computer-readable mediumsuch as system memory or other memory. In some cases, the software 930may not be directly executable by the processor but may cause a computer(e.g., when compiled and executed) to perform functions describedherein.

Transceiver 935 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. For example, thetransceiver 935 may represent a wireless transceiver and may communicatebi-directionally with another wireless transceiver. The transceiver 935may also include a modem to modulate the packets and provide themodulated packets to the antennas for transmission, and to demodulatepackets received from the antennas.

In some cases, the wireless device may include a single antenna 940.However, in some cases the device may have more than one antenna 940,which may be capable of concurrently transmitting or receiving multiplewireless transmissions.

I/O controller 945 may manage input and output signals for device 905.I/O controller 945 may also manage peripherals not integrated intodevice 905. In some cases, I/O controller 945 may represent a physicalconnection or port to an external peripheral. In some cases, I/Ocontroller 945 may utilize an operating system such as iOS®, ANDROID®,MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operatingsystem. In other cases, I/O controller 945 may represent or interactwith a modem, a keyboard, a mouse, a touchscreen, or a similar device.In some cases, I/O controller 945 may be implemented as part of aprocessor. In some cases, a user may interact with device 905 via I/Ocontroller 945 or via hardware components controlled by I/O controller945.

FIG. 10 shows a block diagram 1000 of a wireless device 1005 thatsupports uplink transmission parameter selection during random accessmessage transmission and retransmission in accordance with variousaspects of the present disclosure. Wireless device 1005 may be anexample of aspects of a base station 105 as described with reference toFIG. 1. Wireless device 1005 may include receiver 1010, base stationrandom access manager 1015, and transmitter 1020. Wireless device 1005may also include a processor. Each of these components may be incommunication with one another (e.g., via one or more buses).

Receiver 1010 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to uplinktransmission parameter selection during random access messagetransmission and retransmission, etc.). Information may be passed on toother components of the device. The receiver 1010 may be an example ofaspects of the transceiver 1335 described with reference to FIG. 13.

Base station random access manager 1015 may be an example of aspects ofthe base station random access manager 1315 described with reference toFIG. 13.

Base station random access manager 1015 and/or at least some of itsvarious sub-components may be implemented in hardware, software executedby a processor, firmware, or any combination thereof. If implemented insoftware executed by a processor, the functions of the base stationrandom access manager 1015 and/or at least some of its varioussub-components may be executed by a general-purpose processor, a DSP, anASIC, an FPGA or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described in the presentdisclosure.

The base station random access manager 1015 and/or at least some of itsvarious sub-components may be physically located at various positions,including being distributed such that portions of functions areimplemented at different physical locations by one or more physicaldevices. In some examples, base station random access manager 1015and/or at least some of its various sub-components may be a separate anddistinct component in accordance with various aspects of the presentdisclosure. In other examples, base station random access manager 1015and/or at least some of its various sub-components may be combined withone or more other hardware components, including but not limited to anI/O component, a transceiver, a network server, another computingdevice, one or more other components described in the presentdisclosure, or a combination thereof in accordance with various aspectsof the present disclosure.

Base station random access manager 1015 may receive, via a firstreception beam, a first random access message (e.g., a random accesspreamble) from a wireless device, transmit, to the wireless device, arandom access response message based on the first random access message,and receive, in a subframe allocated for the first random accessmessage, a second random access message (e.g., connection request) fromthe wireless device.

Transmitter 1020 may transmit signals generated by other components ofthe device. In some examples, the transmitter 1020 may be collocatedwith a receiver 1010 in a transceiver module. For example, thetransmitter 1020 may be an example of aspects of the transceiver 1335described with reference to FIG. 13. The transmitter 1020 may include asingle antenna, or it may include a set of antennas.

FIG. 11 shows a block diagram 1100 of a wireless device 1105 thatsupports uplink transmission parameter selection during random accessmessage transmission and retransmission in accordance with variousaspects of the present disclosure. Wireless device 1105 may be anexample of aspects of a wireless device 1005 or a base station 105 asdescribed with reference to FIGS. 1 and 10. Wireless device 1105 mayinclude receiver 1110, base station random access manager 1115, andtransmitter 1120. Wireless device 1105 may also include a processor.Each of these components may be in communication with one another (e.g.,via one or more buses).

Receiver 1110 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related to uplinktransmission parameter selection during random access messagetransmission and retransmission, etc.). Information may be passed on toother components of the device. The receiver 1110 may be an example ofaspects of the transceiver 1335 described with reference to FIG. 13.

Base station random access manager 1115 may be an example of aspects ofthe base station random access manager 1315 described with reference toFIG. 13.

Base station random access manager 1115 may also include beam receptioncomponent 1125, response message component 1130, and message receiver1135.

Beam reception component 1125 may receive, via a first reception beam, afirst random access message, such as a random access preamble, from awireless device.

Response message component 1130 may transmit, to the wireless device, arandom access response message based on the first random access message.

Message receiver 1135 may receive, in a subframe allocated for the firstrandom access message, a second random access message, such as aconnection request message, from the wireless device which may includereceiving the second random access message via a second reception beamdifferent from the first reception beam. In some cases, the secondrandom access message may be received over a different set of randomaccess resources, as compared to the first random access message.

Transmitter 1120 may transmit signals generated by other components ofthe device. In some examples, the transmitter 1120 may be collocatedwith a receiver 1110 in a transceiver module. For example, thetransmitter 1120 may be an example of aspects of the transceiver 1335described with reference to FIG. 13. The transmitter 1120 may include asingle antenna, or it may include a set of antennas.

FIG. 12 shows a block diagram 1200 of a base station random accessmanager 1215 that supports uplink transmission parameter selectionduring random access message transmission and retransmission inaccordance with various aspects of the present disclosure. The basestation random access manager 1215 may be an example of aspects of abase station random access manager 1315 described with reference toFIGS. 10, 11, and 13. The base station random access manager 1215 mayinclude beam reception component 1220, response message component 1225,message receiver 1230, resource indication component 1235, andretransmission number component 1240. Each of these modules maycommunicate, directly or indirectly, with one another (e.g., via one ormore buses).

Beam reception component 1220 may receive, via a first reception beam, afirst random access message from a wireless device.

Response message component 1225 may transmit, to the wireless device, arandom access response message based on the first random access message.

Message receiver 1230 may receive, in a subframe allocated for the firstrandom access message, a second random access message from the wirelessdevice which may include receiving the second random access message viaa second reception beam different from the first reception beam.

Resource indication component 1235 may transmit, to the wireless device,an indication of one or more resources for transmission of the secondrandom access message.

Retransmission number component 1240 may transmit a maximumretransmission number corresponding to the second random access message.In some cases, the maximum retransmission number is associated with atleast one of a total number of retransmission attempts of the secondrandom access message or a maximum number of retransmission attempts ofthe second random access message for each of a set of uplinktransmission powers. In some cases, the retransmission number component1240 may further transmit an indication of ramping up the uplinktransmit power, utilizing different RACH resources, or both, forretransmission of the first or the second random access message.

FIG. 13 shows a diagram of a system 1300 including a device 1305 thatsupports uplink transmission parameter selection during random accessmessage transmission and retransmission in accordance with variousaspects of the present disclosure. Device 1305 may be an example of orinclude the components of base station 105 as described above, e.g.,with reference to FIG. 1. Device 1305 may include components forbi-directional voice and data communications including components fortransmitting and receiving communications, including base station randomaccess manager 1315, processor 1320, memory 1325, software 1330,transceiver 1335, antenna 1340, network communications manager 1345, andbase station communications manager 1350. These components may be inelectronic communication via one or more busses (e.g., bus 1310). Device1305 may communicate wirelessly with one or more UEs 115.

Processor 1320 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, anFPGA, a programmable logic device, a discrete gate or transistor logiccomponent, a discrete hardware component, or any combination thereof).In some cases, processor 1320 may be configured to operate a memoryarray using a memory controller. In other cases, a memory controller maybe integrated into processor 1320. Processor 1320 may be configured toexecute computer-readable instructions stored in a memory to performvarious functions (e.g., functions or tasks supporting uplinktransmission parameter selection during random access messagetransmission and retransmission).

Memory 1325 may include RAM and ROM. The memory 1325 may storecomputer-readable, computer-executable software 1330 includinginstructions that, when executed, cause the processor to perform variousfunctions described herein. In some cases, the memory 1325 may contain,among other things, a BIOS which may control basic hardware and/orsoftware operation such as the interaction with peripheral components ordevices.

Software 1330 may include code to implement aspects of the presentdisclosure, including code to support uplink transmission parameterselection during random access message transmission and retransmission.Software 1330 may be stored in a non-transitory computer-readable mediumsuch as system memory or other memory. In some cases, the software 1330may not be directly executable by the processor but may cause a computer(e.g., when compiled and executed) to perform functions describedherein.

Transceiver 1335 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. For example, thetransceiver 1335 may represent a wireless transceiver and maycommunicate bi-directionally with another wireless transceiver. Thetransceiver 1335 may also include a modem to modulate the packets andprovide the modulated packets to the antennas for transmission, and todemodulate packets received from the antennas.

In some cases, the wireless device may include a single antenna 1340.However, in some cases the device may have more than one antenna 1340,which may be capable of concurrently transmitting or receiving multiplewireless transmissions.

Network communications manager 1345 may manage communications with thecore network (e.g., via one or more wired backhaul links). For example,the network communications manager 1345 may manage the transfer of datacommunications for client devices, such as one or more UEs 115.

Base station communications manager 1350 may manage communications withother base station 105, and may include a controller or scheduler forcontrolling communications with UEs 115 in cooperation with other basestations 105. For example, the base station communications manager 1350may coordinate scheduling for transmissions to UEs 115 for variousinterference mitigation techniques such as beamforming or jointtransmission. In some examples, base station communications manager 1350may provide an X2 interface within an LTE/LTE-A wireless communicationnetwork technology to provide communication between base stations 105.

FIG. 14 shows a flowchart illustrating a method 1400 for uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. The operations of method 1400 may be implementedby a UE 115 or its components as described herein. For example, theoperations of method 1400 may be performed by a UE random access manageras described with reference to FIGS. 6 through 9. In some examples, a UE115 may execute a set of codes to control the functional elements of thedevice to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects of the functions describedbelow using special-purpose hardware.

At 1405, the UE 115 may identify a first uplink transmission beam for arandom access procedure. The operations of block 1405 may be performedaccording to the methods described with reference to FIGS. 1 through 5.In certain examples, aspects of the operations of block 1405 may beperformed by a transmission beam identifier as described with referenceto FIGS. 6 through 9.

At 1410, the UE 115 may transmit, at a first uplink transmission power,a random access preamble based at least in part on the first uplinktransmission beam. The operations of block 1410 may be performedaccording to the methods described with reference to FIGS. 1 through 5.In certain examples, aspects of the operations of block 1410 may beperformed by a random access transmitter as described with reference toFIGS. 6 through 9.

At 1415, the UE 115 may receive a random access response messagetransmitted from a base station in response to the random accesspreamble. The operations of block 1415 may be performed according to themethods described with reference to FIGS. 1 through 5. In certainexamples, aspects of the operations of block 1415 may be performed by arandom access receiver as described with reference to FIGS. 6 through 9.

At 1420, the UE 115 may identify a second uplink transmission beam forthe random access procedure. The operations of block 1420 may beperformed according to the methods described with reference to FIGS. 1through 5. In certain examples, aspects of the operations of block 1420may be performed by a transmission power component as described withreference to FIGS. 6 through 9.

At 1425, the UE 115 may select a second uplink transmission power basedat least in part on a path loss associated with the random accessprocedure and the identified second uplink transmission beam. Theoperations of block 1420 may be performed according to the methodsdescribed with reference to FIGS. 1 through 5. In certain examples,aspects of the operations of block 1420 may be performed by atransmission beam identifier as described with reference to FIGS. 6through 9.

At 1430, the UE 115 may transmit, to the base station, a connectionrequest message based at least in part on the second uplink transmissionpower and the identified second uplink transmission beam. The operationsof block 1425 may be performed according to the methods described withreference to FIGS. 1 through 5. In certain examples, aspects of theoperations of block 1425 may be performed by a random access transmitteras described with reference to FIGS. 6 through 9.

FIG. 15 shows a flowchart illustrating a method 1500 for uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. The operations of method 1500 may be implementedby a UE 115 or its components as described herein. For example, theoperations of method 1500 may be performed by a UE random access manageras described with reference to FIGS. 6 through 9. In some examples, a UE115 may execute a set of codes to control the functional elements of thedevice to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects of the functions describedbelow using special-purpose hardware.

At 1505, the UE 115 may transmit, at a first uplink transmission powerand over a first random access resource, a random access preamble usinga first uplink transmission beam. The operations of block 1505 may beperformed according to the methods described with reference to FIGS. 1through 5. In certain examples, aspects of the operations of block 1505may be performed by a random access transmitter as described withreference to FIGS. 6 through 9.

At 1510, the UE 115 may receive a random access response messagetransmitted from a base station in response to the random accesspreamble. The operations of block 1510 may be performed according to themethods described with reference to FIGS. 1 through 5. In certainexamples, aspects of the operations of block 1510 may be performed by arandom access receiver as described with reference to FIGS. 6 through 9.

At 1515, the UE 115 may transmit, to the base station, a connectionrequest based at least in part on the random access response message.The operations of block 1515 may be performed according to the methodsdescribed with reference to FIGS. 1 through 5. In certain examples,aspects of the operations of block 1515 may be performed by a randomaccess transmitter as described with reference to FIGS. 6 through 9.

At 1520, the UE 115 may receive, from the base station, a signalindicating the UE to ramp up transmit power, select a different randomresource, or both. In some cases, the indication may be in response tothe base station inferring that a RACH collision has occurred due to theabsence of a connection request message from the UE, changingcommunication conditions, etc. The operations of block 1510 may beperformed according to the methods described with reference to FIGS. 1through 5. In certain examples, aspects of the operations of block 1510may be performed by a random access receiver as described with referenceto FIGS. 6 through 9.

At 1525, the UE 115 may retransmit the connection request message basedat least in part on an absence of a response to the connection requestand in accordance with a maximum retransmission number associated withthe connection request message. In some cases, the UE may autonomouslydecide to select different parameters for communicating theretransmission to the base station, for instance, by selecting adifferent transmission power, beam, or RACH resource than previouslyused in the initial RACH request message, or in the first transmissionof the connection request message, or any other previousretransmission(s). The operations of block 1520 may be performedaccording to the methods described with reference to FIGS. 1 through 5.In certain examples, aspects of the operations of block 1525 may beperformed by a retransmission component as described with reference toFIGS. 6 through 9.

FIG. 16 shows a flowchart illustrating a method 1600 for uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. The operations of method 1600 may be implementedby a UE 115 or its components as described herein. For example, theoperations of method 1600 may be performed by a UE random access manageras described with reference to FIGS. 6 through 9. In some examples, a UE115 may execute a set of codes to control the functional elements of thedevice to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects of the functions describedbelow using special-purpose hardware.

At 1605, the UE 115 may transmit, to a base station, a random accesspreamble using a first set of resources allocated for transmission ofthe random access preamble. The operations of block 1605 may beperformed according to the methods described with reference to FIGS. 1through 5. In certain examples, aspects of the operations of block 1605may be performed by a random access transmitter as described withreference to FIGS. 6 through 9.

At 1610, the UE 115 may receive a random access response messagetransmitted by the base station in response to the random accesspreamble. The operations of block 1610 may be performed according to themethods described with reference to FIGS. 1 through 5. In certainexamples, aspects of the operations of block 1610 may be performed by arandom access receiver as described with reference to FIGS. 6 through 9.

At 1615, the UE 115 may determine a second set of resources fortransmission of a connection request message. The operations of block1615 may be performed according to the methods described with referenceto FIGS. 1 through 5. In certain examples, aspects of the operations ofblock 1615 may be performed by a subframe identifier as described withreference to FIGS. 6 through 9.

At 1620, the UE 115 may transmit, using the second set of resources, theconnection request message in response to the random access responsemessage. The operations of block 1620 may be performed according to themethods described with reference to FIGS. 1 through 5. In certainexamples, aspects of the operations of block 1620 may be performed by arandom access transmitter as described with reference to FIGS. 6 through9.

FIG. 17 shows a flowchart illustrating a method 1700 for uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. The operations of method 1700 may be implementedby a base station 105 or its components as described herein. Forexample, the operations of method 1700 may be performed by a basestation random access manager as described with reference to FIGS. 10through 13. In some examples, a base station 105 may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the basestation 105 may perform aspects of the functions described below usingspecial-purpose hardware.

At block 1705 the base station 105 may receive, via a first receptionbeam, a random access preamble from a wireless device. The operations ofblock 1705 may be performed according to the methods described withreference to FIGS. 1 through 5. In certain examples, aspects of theoperations of block 1705 may be performed by a beam reception componentas described with reference to FIGS. 10 through 13.

At block 1710 the base station 105 may transmit, to the wireless device,a random access response message based at least in part on the firstrandom access message. The operations of block 1710 may be performedaccording to the methods described with reference to FIGS. 1 through 5.In certain examples, aspects of the operations of block 1710 may beperformed by a response message component as described with reference toFIGS. 10 through 13.

At block 1715 the base station 105 may receive, in a subframe allocatedfor the random access preamble, a connection request message from thewireless device. The operations of block 1715 may be performed accordingto the methods described with reference to FIGS. 1 through 5. In certainexamples, aspects of the operations of block 1715 may be performed by amessage receiver as described with reference to FIGS. 10 through 13.

FIG. 18 shows a flowchart illustrating a method 1800 for uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. The operations of method 1500 may be implementedby a base station 105 or its components as described herein. Forexample, the operations of method 1800 may be performed by a basestation random access manager as described with reference to FIGS. 10through 13. In some examples, a base station 105 may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the basestation 105 may perform aspects of the functions described below usingspecial-purpose hardware.

At 1805, the base station 105 may receive, at a first uplinktransmission power and over a first random access resource, a randomaccess preamble on a first uplink transmission beam. The operations ofblock 1805 may be performed according to the methods described withreference to FIGS. 1 through 5. In certain examples, aspects of theoperations of block 1805 may be performed by a receiver as describedwith reference to FIGS. 10 through 13.

At 1810, the base station 105 may transmit a random access responsemessage in response to the random access preamble. The operations ofblock 1810 may be performed according to the methods described withreference to FIGS. 1 through 5. In certain examples, aspects of theoperations of block 1810 may be performed by a base station randomaccess manager, or a transmitter, as described with reference to FIGS.10 through 13.

At 1815, the base station 105 may receive a connection request based atleast in part on the random access response message. The operations ofblock 1815 may be performed according to the methods described withreference to FIGS. 1 through 5. In certain examples, aspects of theoperations of block 1815 may be performed by a base station randomaccess manager, or a receiver, as described with reference to FIGS. 10through 13.

At 1820, the base station 105 may transmit a signal indicating the UE toramp up transmit power, select a different random resource, or both. Insome cases, the indication may be in response to the base station 105inferring that a RACH collision has occurred due to the absence of aconnection request message from the UE, changing communicationconditions, etc. The operations of block 1820 may be performed accordingto the methods described with reference to FIGS. 1 through 5. In certainexamples, aspects of the operations of block 1820 may be performed by atransmitter as described with reference to FIGS. 10 through 13.

At 1825, the base station 105 may receive the retransmitted connectionrequest message based at least in part on an absence of a response tothe connection request and in accordance with a maximum retransmissionnumber associated with the connection request message. In some cases,the UE 115 may autonomously decide to select different parameters forcommunicating the retransmission to the base station 105, for instance,by selecting a different transmission power, beam, or RACH resource thanpreviously used in the initial RACH request message, or in the firsttransmission of the connection request message, or any other previousretransmission(s). The operations of block 1850 may be performedaccording to the methods described with reference to FIGS. 1 through 5.In certain examples, aspects of the operations of block 1825 may beperformed by a receiver as described with reference to FIGS. 10 through13.

FIG. 19 shows a flowchart illustrating a method 1900 for uplinktransmission parameter selection during random access messagetransmission and retransmission in accordance with various aspects ofthe present disclosure. The operations of method 1900 may be implementedby a UE 115 or its components as described herein. For example, theoperations of method 1900 may be performed by a UE random access manageras described with reference to FIGS. 6 through 9. In some examples, a UE115 may execute a set of codes to control the functional elements of thedevice to perform the functions described below. Additionally oralternatively, the UE 115 may perform aspects of the functions describedbelow using special-purpose hardware.

At 1905, the UE 115 may transmit, to a base station, a random accesspreamble as part of a random access procedure. The operations of block1905 may be performed according to the methods described with referenceto FIGS. 1 through 5. In certain examples, aspects of the operations ofblock 1905 may be performed by a random access transmitter as describedwith reference to FIGS. 6 through 9.

At 1910, the UE 115 may receive a random access response messagetransmitted from the base station 105 in response to the random accesspreamble. The operations of block 1910 may be performed according to themethods described with reference to FIGS. 1 through 5. In certainexamples, aspects of the operations of block 1910 may be performed by arandom access receiver as described with reference to FIGS. 6 through 9.

At 1915, the UE 115 may identify a first uplink transmission beam forthe random access procedure. The operations of block 1915 may beperformed according to the methods described with reference to FIGS. 1through 5. In certain examples, aspects of the operations of block 1915may be performed by a transmission beam identifier as described withreference to FIGS. 6 through 9.

At 1920, the UE 115 may transmit, to the base station, a connectionrequest message based at least in part on the random access responsemessage, the connection request being transmitted using the first uplinktransmission beam and at a first uplink transmission power. Theoperations of block 1920 may be performed according to the methodsdescribed with reference to FIGS. 1 through 5. In certain examples,aspects of the operations of block 1920 may be performed by a randomaccess transmitter as described with reference to FIGS. 6 through 9.

At 1925, the UE 115 may identify a second uplink transmission beamdifferent from the first uplink transmission beam. The operations ofblock 1925 may be performed according to the methods described withreference to FIGS. 1 through 5. In certain examples, aspects of theoperations of block 1925 may be performed by a transmission beamidentifier as described with reference to FIGS. 6 through 9.

At 1930, the UE 115 may select a second uplink transmission power basedat least in part on a path loss associated with the random accessprocedure and the identified second uplink transmission beam. Theoperations of block 1930 may be performed according to the methodsdescribed with reference to FIGS. 1 through 5. In certain examples,aspects of the operations of block 1930 may be performed by a randomaccess transmitter, or a transmission power component, as described withreference to FIGS. 6 through 9

At 1935, the UE 115 may retransmit the connection request message basedat least in part on the second uplink transmission beam and the seconduplink transmission power. The operations of block 1935 may be performedaccording to the methods described with reference to FIGS. 1 through 5.In certain examples, aspects of the operations of block 1935 may beperformed by a random access transmitter as described with reference toFIGS. 6 through 9.

It should be noted that the methods described above describe possibleimplementations, and that the operations and the steps may be rearrangedor otherwise modified and that other implementations are possible.Furthermore, aspects from two or more of the methods may be combined.

Techniques described herein may be used for various wirelesscommunications systems such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and other systems.The terms “system” and “network” are often used interchangeably. A codedivision multiple access (CDMA) system may implement a radio technologysuch as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc.CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releasesmay be commonly referred to as CDMA2000 1×, 1×, etc. IS-856 (TIA-856) iscommonly referred to as CDMA2000 1×EV-DO, High Rate Packet Data (HRPD),etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. Atime division multiple access (TDMA) system may implement a radiotechnology such as Global System for Mobile Communications (GSM).

An orthogonal frequency division multiple access (OFDMA) system mayimplement a radio technology such as Ultra Mobile Broadband (UMB),Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM,etc. UTRA and E-UTRA are part of Universal Mobile Telecommunicationssystem (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A)are releases of Universal Mobile Telecommunications System (UMTS) thatuse E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, NR, and Global System forMobile communications (GSM) are described in documents from theorganization named “3rd Generation Partnership Project” (3GPP). CDMA2000and UMB are described in documents from an organization named “3rdGeneration Partnership Project 2” (3GPP2). The techniques describedherein may be used for the systems and radio technologies mentionedabove as well as other systems and radio technologies. While aspects ofan LTE or an NR system may be described for purposes of example, and LTEor NR terminology may be used in much of the description, the techniquesdescribed herein are applicable beyond LTE or NR applications.

In LTE/LTE-A networks, including such networks described herein, theterm evolved node B (eNB) may be generally used to describe the basestations. The wireless communications system or systems described hereinmay include a heterogeneous LTE/LTE-A or NR network in which differenttypes of eNBs provide coverage for various geographical regions. Forexample, each eNB, gNB or base station may provide communicationcoverage for a macro cell, a small cell, or other types of cell. Theterm “cell” may be used to describe a base station, a carrier orcomponent carrier associated with a base station, or a coverage area(e.g., sector, etc.) of a carrier or base station, depending on context.

Base stations may include or may be referred to by those skilled in theart as a base transceiver station, a radio base station, an accesspoint, a radio transceiver, a NodeB, eNodeB (eNB), next generation NodeB(gNB), Home NodeB, a Home eNodeB, or some other suitable terminology.The geographic coverage area for a base station may be divided intosectors making up only a portion of the coverage area. The wirelesscommunications system or systems described herein may include basestations of different types (e.g., macro or small cell base stations).The UEs described herein may be able to communicate with various typesof base stations and network equipment including macro eNBs, small celleNBs, gNBs, relay base stations, and the like. There may be overlappinggeographic coverage areas for different technologies.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEswith service subscriptions with the network provider. A small cell is alower-powered base station, as compared with a macro cell, that mayoperate in the same or different (e.g., licensed, unlicensed, etc.)frequency bands as macro cells. Small cells may include pico cells,femto cells, and micro cells according to various examples. A pico cell,for example, may cover a small geographic area and may allowunrestricted access by UEs with service subscriptions with the networkprovider. A femto cell may also cover a small geographic area (e.g., ahome) and may provide restricted access by UEs having an associationwith the femto cell (e.g., UEs in a closed subscriber group (CSG), UEsfor users in the home, and the like). An eNB for a macro cell may bereferred to as a macro eNB. An eNB for a small cell may be referred toas a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB maysupport one or multiple (e.g., two, three, four, and the like) cells(e.g., component carriers).

The wireless communications system or systems described herein maysupport synchronous or asynchronous operation. For synchronousoperation, the base stations may have similar frame timing, andtransmissions from different base stations may be approximately alignedin time. For asynchronous operation, the base stations may havedifferent frame timing, and transmissions from different base stationsmay not be aligned in time. The techniques described herein may be usedfor either synchronous or asynchronous operations.

The downlink transmissions described herein may also be called forwardlink transmissions while the uplink transmissions may also be calledreverse link transmissions. Each communication link describedherein—including, for example, wireless communications system 100 and200 of FIGS. 1 and 2—may include one or more carriers, where eachcarrier may be a signal made up of multiple sub-carriers (e.g., waveformsignals of different frequencies).

The description set forth herein, in connection with the appendeddrawings, describes example configurations and does not represent allthe examples that may be implemented or that are within the scope of theclaims. The term “exemplary” used herein means “serving as an example,instance, or illustration,” and not “preferred” or “advantageous overother examples.” The detailed description includes specific details forthe purpose of providing an understanding of the described techniques.These techniques, however, may be practiced without these specificdetails. In some instances, well-known structures and devices are shownin block diagram form in order to avoid obscuring the concepts of thedescribed examples.

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of at least one of A, B, or C meansA or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, asused herein, the phrase “based on” shall not be construed as a referenceto a closed set of conditions. For example, an exemplary step that isdescribed as “based on condition A” may be based on both a condition Aand a condition B without departing from the scope of the presentdisclosure. In other words, as used herein, the phrase “based on” shallbe construed in the same manner as the phrase “based at least in parton.”

Computer-readable media includes both non-transitory computer storagemedia and communication media including any medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage medium may be any available medium that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, non-transitory computer-readable media maycomprise RAM, ROM, electrically erasable programmable read only memory(EEPROM), compact disk (CD) ROM or other optical disk storage, magneticdisk storage or other magnetic storage devices, or any othernon-transitory medium that can be used to carry or store desired programcode means in the form of instructions or data structures and that canbe accessed by a general-purpose or special-purpose computer, or ageneral-purpose or special-purpose processor. Also, any connection isproperly termed a computer-readable medium. For example, if the softwareis transmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave are included in the definition of medium. Disk and disc,as used herein, include CD, laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

The description herein is provided to enable a person skilled in the artto make or use the disclosure. Various modifications to the disclosurewill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other variations withoutdeparting from the scope of the disclosure. Thus, the disclosure is notlimited to the examples and designs described herein, but is to beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method for wireless communication, comprising:receiving, at a first uplink transmission power and over a first randomaccess resource, a random access preamble transmitted from a userequipment (UE) over a first uplink transmission beam; transmitting arandom access response message in response to the random accesspreamble; receiving a connection request based at least in part on therandom access response message; transmitting, to the UE, a signalindicating the UE to ramp up transmit power, select a different randomaccess resource, or both; and receiving, at a second uplink transmissionpower, a retransmitted random access preamble or connection requestbased at least in part on an absence of a response to the random accesspreamble or connection request, wherein the second uplink transmissionpower is ramped up from the first uplink transmission power, and whereinthe retransmission is in accordance with a maximum retransmission numberassociated with the random access preamble or connection request.
 2. Themethod of claim 1, further comprising: participating in a beamrefinement process; and adjusting at least one transmit beam based atleast in part on the beam refinement process, wherein the random accessresponse message is transmitted based at least in part on the adjustedat least one transmit beam.
 3. The method of claim 1, wherein receivingthe connection request further comprises: receiving the connectionrequest via a second uplink transmission beam that is different from thefirst uplink transmission beam.
 4. The method of claim 1, wherein therandom access response message comprises an uplink transmission powercommand for the UE.
 5. The method of claim 4, wherein the second uplinktransmission power is adjusted by the UE based at least in part on theuplink transmission power command and a path loss associated with therandom access response message.
 6. The method of claim 1, wherein thesignal indicating the UE to ramp up transmit power, select a differentrandom access resource, or both comprises a master information block(MIB) or a master system information block (MSIB).
 7. The method ofclaim 1, further comprising: identifying a second random access resourcefor receiving the random access preamble; monitoring, based at least inpart on transmitting the random access response message, the secondrandom access resource; and receiving, based at least in part on themonitoring, the connection request over the second random accessresource.
 8. The method of claim 1, further comprising: transmitting, tothe UE, multiple synchronization signals, wherein receiving theconnection request further comprises receiving the connection requestvia a second uplink transmission beam for the connection request basedat least in part on one or more of the multiple synchronization signals.9. The method of claim 1, further comprising: receiving, via a seconduplink transmission beam that is different than the first uplinktransmission beam, a retransmission of the connection request.
 10. Themethod of claim 1, further comprising: transmitting, to the UE, amaximum retransmission number, wherein receiving the retransmittedrandom access preamble or connection request is based at least in parton the transmitting the maximum retransmission number.
 11. The method ofclaim 10, wherein the maximum retransmission number is associated withat least one of a total number of retransmission attempts of theconnection request or a maximum number of retransmission attempts of theconnection request for each of a plurality of uplink transmissionpowers.
 12. The method of claim 1, further comprising: transmitting, tothe UE, a retransmission grant, wherein receiving the retransmittedrandom access preamble or the connection request is based at least inpart on transmitting the retransmission grant.
 13. An apparatus forwireless communication, comprising: a processor; memory coupled with theprocessor; and instructions stored in the memory and executable by theprocessor to cause the apparatus to: receive, at a first uplinktransmission power and over a first random access resource, a randomaccess preamble transmitted from a user equipment (UE) over a firstuplink transmission beam; transmit a random access response message inresponse to the random access preamble; receive a connection requestbased at least in part on the random access response message; transmit,to the UE, a signal indicating the UE to ramp up transmit power, selecta different random access resource, or both; and receive, at a seconduplink transmission power, a retransmitted random access preamble orconnection request based at least in part on an absence of a response tothe random access preamble or connection request, wherein the seconduplink transmission power is ramped up from the first uplinktransmission power, and wherein the retransmission is in accordance witha maximum retransmission number associated with the random accesspreamble or connection request.
 14. The apparatus of claim 13, whereinthe instructions are further executable by the processor to cause theapparatus to: participate in a beam refinement process; and adjust atleast one transmit beam based at least in part on the beam refinementprocess, wherein the random access response message is transmitted basedat least in part on the adjusted at least one transmit beam.
 15. Theapparatus of claim 13, wherein the instructions to the connectionrequest are further executable by the processor to cause the apparatusto: receive the connection request via a second uplink transmission beamthat is different from the first uplink transmission beam.
 16. Theapparatus of claim 13, wherein the random access response messagecomprises an uplink transmission power command for the UE.
 17. Theapparatus of claim 16, wherein the second uplink transmission power isadjusted by the UE based at least in part on the uplink transmissionpower command and a path loss associated with the random access responsemessage.
 18. The apparatus of claim 13, wherein the signal indicatingthe UE to ramp up transmit power, select a different random accessresource, or both comprises a master information block (MIB) or a mastersystem information block (MSIB).
 19. The apparatus of claim 13, whereinthe instructions are further executable by the processor to cause theapparatus to: identify a second random access resource for receiving therandom access preamble; monitoring, base at least in part ontransmitting the random access response message, the second randomaccess resource; and receive, based at least in part on the monitoring,the connection request over the second random access resource.
 20. Theapparatus of claim 13, wherein the instructions are further executableby the processor to cause the apparatus to: transmit, to the UE,multiple synchronization signals, wherein receiving the connectionrequest further comprises receiving the connection request via a seconduplink transmission beam for the connection request based at least inpart on one or more of the multiple synchronization signals.
 21. Theapparatus of claim 13, wherein the instructions are further executableby the processor to cause the apparatus to: receive, via a second uplinktransmission beam that is different than the first uplink transmissionbeam, a retransmission of the connection request.
 22. The apparatus ofclaim 13, wherein the instructions are further executable by theprocessor to cause the apparatus to: transmit, to the UE, a maximumretransmission number, wherein receiving the retransmitted random accesspreamble or connection request is based at least in part on thetransmitting the maximum retransmission number.
 23. The apparatus ofclaim 22, wherein the maximum retransmission number is associated withat least one of a total number of retransmission attempts of theconnection request or a maximum number of retransmission attempts of theconnection request for each of a plurality of uplink transmissionpowers.
 24. The apparatus of claim 13, wherein the instructions arefurther executable by the processor to cause the apparatus to: transmit,to the UE, a retransmission grant, wherein receiving the retransmittedrandom access preamble or the connection request is based at least inpart on transmitting the retransmission grant.
 25. An apparatus forwireless communication, comprising: means for receiving, at a firstuplink transmission power and over a first random access resource, arandom access preamble transmitted from a user equipment (UE) over afirst uplink transmission beam; means for transmitting a random accessresponse message in response to the random access preamble; means forreceiving a connection request based at least in part on the randomaccess response message; means for transmitting, to the UE, a signalindicating the UE to ramp up transmit power, select a different randomaccess resource, or both; and means for receiving, at a second uplinktransmission power, a retransmitted random access preamble or connectionrequest based at least in part on an absence of a response to the randomaccess preamble or connection request, wherein the second uplinktransmission power is ramped up from the first uplink transmissionpower, and wherein the retransmission is in accordance with a maximumretransmission number associated with the random access preamble orconnection request.
 26. The apparatus of claim 25, further comprising:means for participating in a beam refinement process; and means foradjusting at least one transmit beam based at least in part on the beamrefinement process, wherein the random access response message istransmitted based at least in part on the adjusted at least one transmitbeam.
 27. The apparatus of claim 25, wherein the means for theconnection request further comprises: means for receiving the connectionrequest via a second uplink transmission beam that is different from thefirst uplink transmission beam.
 28. A non-transitory computer-readablemedium storing code for wireless communication, the code comprisinginstructions executable by a processor to: receive, at a first uplinktransmission power and over a first random access resource, a randomaccess preamble transmitted from a user equipment (UE) over a firstuplink transmission beam; transmit a random access response message inresponse to the random access preamble; receive a connection requestbased at least in part on the random access response message; transmit,to the UE, a signal indicating the UE to ramp up transmit power, selecta different random access resource, or both; and receive, at a seconduplink transmission power, a retransmitted random access preamble orconnection request based at least in part on an absence of a response tothe random access preamble or connection request, wherein the seconduplink transmission power is ramped up from the first uplinktransmission power, and wherein the retransmission is in accordance witha maximum retransmission number associated with the random accesspreamble or connection request.
 29. The non-transitory computer-readablemedium of claim 28, wherein the instructions are further executable bythe processor to: participate in a beam refinement process; and adjustat least one transmit beam based at least in part on the beam refinementprocess, wherein transmitting the random access response message isbased at least in part on the at least one transmit beam.
 30. Thenon-transitory computer-readable medium of claim 28, wherein theinstructions to the connection request are further executable by theprocessor to: receive the connection request via a second uplinktransmission beam that is different from the first uplink transmissionbeam.